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Messaging ​

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Messaging ​

For AI agents: a documentation index is available at the root level at /llms.txt. Append /llms.txt to any URL for a page-level index, or .md for the markdown version of any page.

Programmable Messaging is deeply integrated in the SignalWire platform. Our robust APIs, SDKs, and application builders are backed by first-class support and a team dedicated to compliance and class-leading delivery rates across all carriers and locations.

SignalWire is your Messaging partner from proof-of-concept to deployment. Get up and running quickly with our Getting Started guides and get registration right the first time with our comprehensive Guide to The Campaign Registry (TCR).

Try it out ​

Send an SMS message ​
SWML ​
RELAY Realtime SDK (Server) ​
REST API ​
version: 1.0.0
sections:
  main:
    - send_sms:
        from_number: "+155512312345"
        to_number: "+15555554321"
        body: "Hello from SignalWire!"
Send an MMS message ​
SWML ​
RELAY Realtime SDK (Server) ​
REST API ​
version: 1.0.0
sections:
  main:
    - send_sms:
        from_number: "+155512312345"
        to_number: "+15555554321"
        media: ["https://mcdn.signalwire.com/images/v2/loud/LogoLarge.jpg"]
Respond to an incoming message ​
SWML ​
RELAY Realtime SDK (Server) ​
version: 1.0.0
sections:
  main:
    - reply:
        body: "The message %{message.body} has been received!"
Forward an incoming message ​
SWML ​
RELAY Realtime SDK (Server) ​
version: 1.0.0
sections:
  main:
    - reply:
        to: "+1xxxxxxxxxx"
        from: "%{message.to}"
        body: "You received a message from %{message.from} to SignalWire number %{message.to}. The message was: %{message.body}"

Choose an API ​

SignalWire’s many API offerings make it quick and easy to send and receive SMS and MMS within an application through a variety of phone number types. There are a few different ways to utilize these services, so we encourage you to browse the documentation for our APIs.

Looking for Chat or PubSub? ​

SignalWire’s Messaging APIs are tailored for SMS and MMS over the PSTN. For non-PSTN applications, check out our Chat APIs.

REST APIs\ \ Use classic HTTP calls to manage brands and campaigns, configure phone numbers, and much more.

Reference ​

Character limits\ \ How message segments are measured and priced. MIME types\ \ Supported media types for MMS.

Frequently asked questions ​

What are the essential steps I need to take to start sending messages? ​
  1. Create a Brand.
  2. Register a Campaign.
  3. Assign phone numbers to the campaign.

Full details are explained in our Registration guide.

Why can't I send or receive messages on my new 10DLC number? ​

As of December 2025, newly purchased US 10DLC numbers do not have messaging capabilities enabled by default.

To enable messaging:

  • Outbound/mixed use: Assign your number to an approved TCR campaign. Messaging is automatically enabled once the number is assigned.
  • Inbound-only use: Contact Support to request inbound messaging enablement.
  • Testing only: Your first purchased number is automatically enabled for Platform Free Trial when paired with a verified mobile number.
What is 10DLC? ​

10DLC is a type of phone number. Short for 10 Digit Local Code, it is a type of phone number that includes an area code followed by 7 additional digits indicating a specific channel. For example, +12345678910, where the “+1” indicates the country, the “234” indicates the area code, and the remaining digits indicate the channel.

What is the difference between 10DLC and Toll-free phone numbers? ​

Toll-free numbers, although slightly more expensive, allow for increased throughput out-of-the-box. They also have a registration process tied to them, however once complete, have a higher deliverability rating than traditional 10DLC numbers.

What is The Campaign Registry? ​

The Campaign Registry is a platform that was created in partnership with a company called Kaleyra and several Mobile Network Operators (MNOs). The platform itself acts as a source of information about every 10DLC number being used for outbound SMS through A2P routes in an effort to discourage spam in the industry. In short, any and all 10DLC numbers that are to be used for SMS in SignalWire’s platform must be registered through the Campaign Registry. You can find more information about the Campaign Registry in-depth here.

Can we programmatically create campaigns and brands? ​

Yes! You can do this through the SignalWire REST APIs. Check out the documentation.

How many messages can I send out? ​

The number of messages you can send out depends on a few different factors. If you are using a toll-free number, there is no real limit outside of throughput in regards to the amount of messages you could feasibly send. With 10DLC, it depends on your registered use case with the Campaign Registry. AT&T provides a limit on the amount of texts per minute you can send to an end-user at the campaign level whereas T-Mobile limits the overall amount of SMS per day you can send to and end user at the brand level. For more information around this, consult our guide to The Campaign Registry.

What content is not allowed? ​

There is some content that is explicitly disallowed from being sent via SMS/MMS with SignalWire. You can see this list in full detail here.

How do I redact the body of a sent message? ​

For compliance, privacy, or moderation use cases, you can redact the body of a previously sent message by sending a PATCH request to /api/messaging/messages/:message_id with a body of "". Only messages in terminal states (delivered, undelivered, failed) are eligible; messages still in progress (queued or initiated) cannot be redacted. Once redacted, the original body is overwritten and cannot be recovered. See the Redact a message API reference for full details.

What are Carrier Passthrough Fees? ​

Carrier Passthrough Fees, also known as Network Access Fees (NAFs), are additional fees that Mobile Network Operators (MNOs), or Carriers, charge on a per-SMS/MMS basis for the ability of that SMS/MMS to be passed-through their network.

Are all the Carrier Passthrough Fees the same? ​

No. Every carrier (MNO) assesses their own rates for inbound and outbound SMS.

How do I get higher throughput? ​

For verified toll-free numbers, you can contact sales at sales@signalwire.com to increase the throughput of those numbers up to 100 MPS for an additional price.

Can I just send SMS/MMS to a specific carrier like Verizon? ​

SignalWire does not provide a way to explicitly send to Verizon end-users or end-users of any other MNO.

Do I register toll-free SMS/MMS traffic? ​

You can verify toll-free traffic by opening a support ticket with us. Our team will follow up with the forms and information we need from you within that support ticket.

Does SignalWire manage opt-outs? ​

No. Customers are responsible for handling inbound stop requests and removing those customers from subscriber lists. Messages should not go out to these numbers again unless they have opted back in via an Unstop request.

What is considered a high opt-out rate? ​

Carriers consider anything more than 5% opt-out to be a high rate for consumers who have opted in and therefore should want to receive these messages.

Can I turn off inbound SMS? ​

Not currently. We have no way to turn off inbound SMS at this time. You can leave your numbers unset up for messaging and nothing will happen when inbound messages come into the numbers though!

Do you have a messaging queue? ​

We do not have a “scheduled” queue, but messages that exceed your throughput will be entered into your Space’s backlog and sent when possible. Read about the backlog and queue system here! The default message backlog is 10,000 for the entire Space. These limits can be increased based on the use case and individual approval following an account verification request.

Am I billed once a message is in the queue? ​

Messages are charged when they are ‘Sent’ successfully - meaning they leave our network without issue. They are charged regardless of whether or not they deliver after they have left our network. You are not charged while your messages are queued or ‘failed’ (failed meaning they never left our network).

Where can I find information on specific error codes? ​

Visit our error code explanation page for details.

The Campaign Registry ​

For AI agents: a documentation index is available at the root level at /llms.txt. Append /llms.txt to any URL for a page-level index, or .md for the markdown version of any page.

If you’re using an application platform (e.g. SignalWire) to send customers messages from a local phone number, you need to register with the Campaign Registry regardless of your use case. In this guide, we will walk you through what the Campaign Registry is and why is it important to register.

The Campaign Registry only applies to 10DLC/local numbers sending messages to local US phone numbers. If you are sending messaging exclusively outside of the US or only from toll-free/shortcode numbers, this guide is not for you!

These pages containing an overview of TCR rules and regulations and FAQs illustrate SignalWire’s most current understanding of carrier plans. Many of these details are still being finalized and could be subject to change, however SignalWire will continue to update this information as TCR evolves.

What is the Campaign Registry? ​

The usage of extended codes for messaging campaigns has increased due to their simplicity and ability to meet the needs of Application-to-Person (A2P) messaging between businesses and customers. As text message volume has increased, some businesses have used the same technology for sending spam text messages. This proliferation of spam is bad for customers, businesses, and the mobile industry overall.

With the above in mind, the Mobile Network Operators (MNOs) have partnered up with a company called Kaleyra to create The Campaign Registry. This platform is a single source of information about 10DLC messaging campaigns throughout the U.S., enabling the MNOs to serve as a record of who sent any given 10DLC message and what they claim to be sending, which can be checked and validated against actual messaging behavior.

The Campaign Registry is about creating a centralized, trusted access point to key information enabling messaging service providers such as SignalWire, to exchange transparency (directly with the MNO’s) in who they are and what they are doing for more predictable and reliable service delivery to end-users.

MNO’s can now have visibility into the “who” and “what” of each messaging campaign which allows them to provide a better quality of service for 10DLC messaging, while service providers like SignalWire can have confidence knowing that they are using an officially sanctioned messaging channel. Businesses can finally benefit from a better quality of service as well as better predictability of success for your messaging campaigns.

How is SignalWire involved? ​

SignalWire is proud to be at the forefront of these changes by working with all of our partners within this new communications ecosystem since its inception. Our priority is ensuring that your business is thriving and there is no disruption. We are fully committed to providing you with these updates as they are received and assisting you with adapting whatever changes are needed.

We will help you register and get your numbers and messaging verified with the registry, and navigate you through all the changes.

Who needs to register? ​

If you’re using an application platform to send messages to the customers, regardless of the conversational nature of the use case, then it is considered A2P (Application-to-Person) and you need to register. In other words, if you are using SignalWire to send messages to customers, you need to register your brand, campaigns, and phone numbers.

Registering with the Campaign Registry is mandatory for all 10DLC traffic to US numbers.

Brands registering with The Campaign Registry will have their legal company name, legal company address, and EIN/Tax ID checked against multiple databases, resulting in either a Verified or Unverified status. Any brand marked Unverified can update their details and resubmit to The Campaign Registry. Each submission incurs a $4 charge.

Given the way that each brand is viewed, every brand that is registered must have a unique EIN. This means that no two brands may share the same EIN or you will risk damaging your companies trust score.

Terms to know ​

There are four categories of players involved in this ecosystem -

  • MNO - These are the Mobile Network Operators aka wireless carriers (Verizon, AT&T, T-Mobile, Sprint, etc.). These are the companies that deliver your messages to the End Users.
  • DCA (Direct Connect Aggregators) - These companies directly connect to the MNO’s gateways and transmit messages on behalf of its customers, such as SignalWire.
  • CSP - This Is SignalWire - A Campaign Service Provider provides messaging services to its customers. A CSP works with its customers (aka Brands) to create and launch new and successful messaging campaigns. SignalWire is a fully registered CSP!
  • Brands - This is the company or entity that will be sending the messages to its End Users.

Registration best practices ​

1

Be transparent and honest ​

You do not want to be in a situation where you are flagged for an error in your brand information or other information requested. More information on this is below.

2

Provide clarity and detail ​

We advise you to be clear and detailed, especially for special use cases. Your use case is what you are using that campaign for. This lets the MNOs know what type of messaging to expect. Here’s a list of the use cases that you can select from. When reviewing a campaign, carriers will look at the campaign description and see if it matches the content of the messages being sent.

Standard Use CaseDescription
2FAAny authentication, verification or one-time passcodes.
Account NotificationsStandard notifications for account holders, relating to and being about a user’s account.
Customer CareAll customer care interactions including, but not limited to, account management and customer support.
Delivery NotificationsNotification about the status of the delivery of a product or service.
Fraud Alert MessagingNotifications regarding potential fraudulent activity on a user’s account.
Higher EducationMessaging created on behalf of colleges or universities, including school districts and education institutions. This use case is NOT for “free to the consumer” messaging models.
Low Volume MixedFor brands that have multiple use cases and require a very low messaging throughput. Examples include: test or demo accounts, small businesses (a single doctor’s office, a single pizza shop, etc.)
MarketingAny communication that includes marketing and/or promotional content.
MixedAny messaging campaign containing 2 to 5 standard use cases.
Polling and votingThe sending of surveys and polling/voting campaigns for non-political arenas.
Public Service AnnouncementInformational messaging to raise an audience’s awareness about important issues.
Security AlertA notification that the security of a system, either software or hardware, has been compromised in some way and there is an action you need to take.

Post-registration review by MNOs is required for all Special Use Cases detailed below.

Special Use CaseDescription
CharityCommunications from a registered charity aimed at providing help and raising money for those in need. 501c3 Tax-Exempt Organizations only.
ProxyPeer-to-peer app-based group messaging with proxy/pooled numbers. Supporting personalized services and non-exposure of personal numbers for enterprise or A2P communications.
EmergencyNotification services designed to support public safety / health during natural disasters, armed conflicts, pandemics and other national or regional emergencies.
SweepstakesAll sweepstakes messaging.
PoliticalPart of organized effort to influence decision making of specific group. Only federal. All campaigns to be pre-vetted.
SocialCommunication with or between closed communities. Examples include: YouTube influencer or celebrity alerts.
Platform Free TrialCSP “Free Trial” Offers for non-paying customers.
Agents and FranchisesBrands that have multiple agents, franchises or offices in the same brand vertical, but require individual localized numbers per agent/location/office.
K-12 EducationCampaigns created for messaging platforms that support schools from grades K-12, and distance learning centers. This is not for post-secondary schools.
UCaaS High VolumeUCaaS companies provide cloud delivered communication services for businesses. Each number assigned to a UCaaS campaign is typically assigned to a different employee of that business and the use cases are varied. This use case is not for any API/automated driven communication. This is for UCaaS campaigns that require higher volume. This use case is only available to approved UCaaS businesses.
UCaaS Low VolumeUCaaS companies provide cloud delivered communication services for businesses. Each number assigned to a UCaaS campaign is typically assigned to a different employee of that business and the use cases are varied. This use case is not for any API/automated driven communication. This use case is only available to approved UCaaS businesses.

3

Provide message templates ​

To verify that your use case is what you say it is, the registry also asks for messages or message templates that you would be sending. Even if you do not expect to have standard messages, try coming up with a few of your most common scenarios, especially if you are going to use the campaign for some common use cases, to help the registry judge your validity. Opt-out language is a must!

When you create a phone number assignment for a brand new campaign, SignalWire has to send information up to our carriers in order to get it connected on their end. For a brand new campaign, this process can take up to 24 hours in normal circumstances. You may see failed or pending for the number assignment order during this time. Rest assured that as soon as it’s completed on the carrier end, you will see it reflected in your portal!

Frequently asked questions ​

Does the TCR requirement apply only to SignalWire? ​

No! This is an industry-wide program and all messaging service providers will need to abide by and be part of this new ecosystem to help ensure messaging compliance among the industry as a whole. SignalWire strictly adheres to all carrier guidelines and regulations when it comes to registrations. Any platform like SignalWire would be required to go through the 10DLC registration process that occurs through The Campaign Registry.

Once the Campaign Registry registration is complete, am I clear to send? ​

No, the campaign must be vetted by our DCA and connections must be accepted upstream before you’re able to send messages, which DCA vetting times can vary typically around 24-48hrs. Once your Campaign is fully vetted and we (SignalWire) inform you that your Campaign is connected, you will need to assign any phone numbers and ensure their assignment status is “Complete” before sending (number assignments may take up to 24hrs to complete). See our next question on DCA Election. Phone numbers must also be assigned to a Campaign ID. Once you are informed by SignalWire via Email that your Campaign is connected and your phone number assignment status is “Complete”, you will be able to start sending.

What is a DCA election? ​

Direct Connect Aggregator (DCAs) are the companies that provide direct connectivity to mobile carrier gateways for the purpose of delivering SMS messaging. In short, a DCA is that organization confirming that the campaign in question is registered with the Campaign Registry. DCA election occurs when our upstream DCA completes their campaign vetting process and the campaign connection request has been accepted.

What is Campaign Verify? ​

Campaign Verify is a third-party SMS campaign verification platform that 527 organizations must go through in order to gain access to the Political use case.

T-Mobile sets a daily SMS limit for each brand. When does that count reset each day? ​

T-Mobile resets their counting towards your daily SMS limit every day at Midnight, US Pacific Time.

What information is required to register? ​

There are essentially two components to become registered:

  1. Brands - First, we need to register your business as a Brand on The Campaign Registry. Once registered, a Brand is given a unique Brand ID that is associated with ALL its campaigns and numbers, and messages. To become a Brand, the registry requires you to provide details about your business such as official company name, website, Tax ID / EIN, company contact name, direct number, and email.
  2. Campaigns - We will then need to register each of your unique campaigns. Once registered, each campaign will also be given a unique ID which will be registered directly with the MNOs (carriers). Information required will be your campaign’s use cases, opt-in/out process, help process, and message samples.
How long does the registration process take? ​

Approximately 3-5 business days (can take shorter or longer depending on the information submitted).

Can I use multiple long code numbers in one campaign? ​

Yes, as long as you have a valid use case for doing so. The maximum is 49 numbers currently; anything more than that will require additional registration for Number Pooling. If this applies to you, open a Support Ticket and we will discuss this in more detail with you!

What if I don't register? ​

If you do not register, you will not be able to send messages from a local US number to another local US number using our platform. Registration is required!

Why can't I send or receive messages on my newly purchased 10DLC number? ​

As of December 2025, newly purchased US 10DLC numbers do not have messaging capabilities enabled by default. Messaging is automatically enabled when you assign the number to an approved TCR campaign.

If you need inbound-only messaging (receiving messages without sending), you can contact Support to request enablement without a full campaign registration.

For testing purposes, your first purchased number is automatically enabled for Platform Free Trial messaging when paired with a verified mobile number.

What if my traffic is P2P (person to person)? ​

SignalWire provides non-consumer messaging routes for businesses, and even if your traffic is “conversational” in nature, it will still need to be registered.

Does this apply to toll-free numbers? ​

No! Toll-Free numbers have to go through a totally unrelated verification process.

What factors will affect my maximum approved throughput? ​

For Brands that are not part of the Russell 2000 list, your default throughput to T-Mobile is 2000 segments per day. External vetting may result in a higher daily throughput. For the other carriers, throughput is determined by use case!

What if my throughput is not high enough for my needs? ​

If the throughput for your campaign does not fit your needs, there are 3rd party vetting partners of the registry that allow for additional vetting. There are added costs associated with that process and added vetting does not guarantee a better outcome.

What exactly is a campaign? ​

The simplest way to describe a campaign is a unique use case. For example, if you send marketing messages and also send alert messages, that would represent two different use cases. However, mixed use case campaigns are possible for lower traffic cases. See the use case table for more details.

How many campaigns will I need? ​

You need one campaign per use case as defined above. Some businesses will require only one use case/campaign (ie…I only send marketing messages). Other businesses may require many use cases/campaigns (ie…I send marketing and alert messages). There are mixed use cases available for businesses that aren’t worried about throughput.

Can I go directly to the Campaign Registry to register? ​

SignalWire has been at the forefront and has become a registered CSP (Campaign Service Provider) so that we can handle registration on your behalf and make it easier for you. That said, if you still prefer to directly go to the Campaign Registry on your own, please reach out to your sales representative for further details and read our guide on Campaign Service Providers.

How will I know when I am fully registered and ready to go? ​

Our dedicated Campaign Registration Specialists will be working closely with you from the time you have submitted your request until all steps have been completed.

Once I am registered, can I send anything I want? ​

No! As mentioned, registration is not a green-light ticket to send anything. In fact, the system is set up so that the MNOs have a way of knowing who and what they are sending allowing for proper enforcement. ALL messaging industry guidelines set forth by the CTIA as well as the MNOs must still be followed to ensure successful message delivery. Those details can be found in our best practices guide.

What if I change my messaging content? ​

If the content change is related to the same use case you used during the initial Campaign registration process, no changes will likely need to be made. However, if the new content you are looking to send is not related to the original use case, you would likely need to have that information changed within the registry. If you are not sure, please contact one of our Campaign Registration Specialists.

What if I want to add an additional number to my current campaign? ​

As mentioned above, as long as there is a valid reason you are needing to add an additional number to a current and active campaign, you are able to do so from the Messaging Campaigns Space on your Dashboard.

What if I want to add a new campaign? ​

You can start the process by accessing the “Messaging Campaigns” tab within your SignalWire Space or by using our API!

Will there be daily messaging limits? ​

T-Mobile has a daily cap on the number of message segments you can send to their network, per brand.

What if I send messages to SignalWire at a higher throughput rate than I am approved for? ​

SignalWire has built a queuing system on our end that will queue up your messages and send them out in accordance with the approved throughput limits. This ensures all your messages will be delivered even if you send them at a higher than approved rate.

My company provides messaging services to multiple companies, how do I go about getting them registered? ​

The Campaign Registry provides for a Reseller persona. In addition, you have the option to register as your own CSP (Campaign Service Provider) directly with the registry. Please reach out to your sales representatives with a support ticket to discuss these options in further detail.

Do these changes affect my shortcodes? ​

No! SignalWire currently offers dedicated short code services. Dedicated short code services are not affected by TCR.

What about other mobile networks? ​

Some MNOs are not currently participating in the Campaign Registry. This whole ecosystem is still very new as well as a large industry change. The Campaign Registry is continuing to work with all the MNO’s and we expect them all to join in the near future. We will provide those updates accordingly. However, SignalWire will still be requiring registration for all 10DLC A2P traffic (regardless of MNO), in order to prevent future hiccups that will occur when other MNOs do eventually join the Campaign Registry.

Do these changes apply everywhere or just in the US? ​

If you are sending messaging exclusively outside of the US, you do not need to register with TCR.

What if I am already registered on the Campaign Registry with another provider, will I need to re-register again when migrating to SignalWire? ​

Yes! Each messaging provider is its own CSP (Campaign Service Provider) and therefore registered uniquely with The Campaign Registry. If you are migrating from another provider, you will need to go through this process again.

If I am migrating from another provider, will my messages be blocked before I am registered with SignalWire? ​

No! Your registration with your current provider will remain in place until you request campaign deactivation. Until your campaign with SignalWire is fully registered, we suggest using your current provider for messaging in the meantime.

What if I switch to another provider in the future, will I need to re-register? ​

Yes! As mentioned, each messaging provider is its own unique CSP (Campaign Service Provider). Therefore, you would need to go through the same process with the new provider when switching over.

Can I have numbers with multiple providers at the same time? ​

Yes! However, you would need to register with each provider accordingly for each set of numbers.

Have any more questions? ​

If you have a question that is not covered in our documentation, please reach out to our support specialists by creating a support ticket from your Dashboard’s top navigation bar.

Campaign Service Providers ​

For AI agents: a documentation index is available at the root level at /llms.txt. Append /llms.txt to any URL for a page-level index, or .md for the markdown version of any page.

If you intend to only create a few Brands and Campaigns then you may choose to have SignalWire act as your CSP and submit your Messaging Campaign Applications on your behalf. If this describes your messaging intentions, see the Brand and Campaign registration guide.

Before digging too deep into acronyms and terms about The Campaign Registry, please reference the Campaign Registry - Everything You Need to Know guide for more background on the policies put into place for 10 Digit Long Code Messaging.

As an ISV (Independent Software Vendor), you have a customer base that each needs their own unique Brand and Campaign registration. As organizing your campaigns becomes increasingly complex, it may be time to look into managing your own campaigns by communicating with The Campaign Registry directly. A Campaign Service Provider has the ability to register or modify their own Brands and Campaigns without needing to involve SignalWire until it is time to associate the newly registered Brands and Campaigns.

How to become a CSP and Getting Started ​

The first step in becoming a Campaign Service Provider will be to register with The Campaign Registry.

Next, you will need to Create a Brand within the Campaign Registry CSP Portal. The initial step for Campaign Registration will be to create a Brand. The information entered will be submitted for Brand Identity Verification so it is important that each field is correctly filled out. This will save time and also save you from pulling your hair out later.

After creating a Brand, you will need to Create a Campaign. A Campaign is a specific use case of your Brand that gives more information on the content that is being sent.

Although the creation of a Brand and Campaign can be done through the CSP Campaign Registry Portal, you are also able to automate this process through the usage of the Campaign Registry APIs. These REST APIs can be easily incorporated into whatever environment your system is based in.

Associating your Brand and Campaigns with SignalWire ​

Once you have created your Brands and Campaigns via The Campaign Registry Dashboard or API, first you must select SignalWire as your upstream Connectivity Partner (CNP), and then you must send Brand and Campaign information directly to SignalWire so your phone numbers can be connected to the newly registered Campaigns. In summary, you provide specific information about the new Brand and Campaign either via Dashboard or API, we review and accept the connection request, and then our upstream Direct Connect Aggregator (DCA) vets and accepts the connection request. Once the DCA election is completed, you may begin assigning your SignalWire phone numbers to your new Campaign!

Associating your Brand and Campaigns with SignalWire via Dashboard ​

If you choose to do this through the Dashboard, you can navigate to Messaging Campaigns and then Create a partner brand. After entering in your name and CSP brand reference via API or Dashboard, you will see your Partner Brand appear in the Dashboard.

After associating your Brands, you must Create Self-Registered Campaigns underneath the Brands that you have created. Again, this can be done via API through the usage of REST APIs, or, can be done through the SignalWire Dashboard underneath the Messaging Campaigns tab.

For the final step, you must Create a Phone Number Assignment to associate your Self-Registered Campaign to your SignalWire Phone number. Navigate to the Campaign Phone Numbers section of the Messaging Campaigns tab in your Dashboard to manually complete this process, or use our REST API.

Please note that if the Brand and Campaign are not loaded into your SignalWire Space, phone numbers will not be able to associate with the Campaign and you will not be able to send messages.

Associating your Brand and Campaigns with SignalWire via API ​

If you prefer to use the REST API to link your Brands and Campaigns with SignalWire, follow these steps:

1

Create a Brand ​

  • Endpoint: Create Brand

  • Method: POST

  • Required Fields:

    • name: The name of your Brand.
    • csp_brand_reference: The approved Brand ID you received from The Campaign Registry.
    • csp_self_registered: Set this field to true to indicate that this Brand is self-registered.

2

Create a Campaign ​

  • Endpoint: Create Campaign

  • Method: POST

  • Required Fields:

    • name: The name of your Campaign.
    • csp_campaign_reference: The approved Campaign ID from The Campaign Registry.

3

Share Campaign with SignalWire ​

  • TCR API Documentation: TCR API - Share Campaign

  • Method: PUT

  • Endpoint: /campaign/{campaignId}/sharing/{upstreamCnpId}

  • Parameters:

    • Replace {campaignId} with the 7-character Campaign ID (e.g., CXXXXXX).
    • Replace {upstreamCnpId} with SignalWire’s CSP ID (SYU5YT8).

4

Create a Phone Number Assignment ​

  • Endpoint: Create Phone Number Assignment

  • Method: POST

  • Required Fields:

    • campaign_id: The ID of the Campaign you want to associate with the phone number.
    • phone_numbers: A list of phone numbers to be assigned to the Campaign.

DCA Election: The Final Step ​

You, like many others, may think that you should be able to start sending messages immediately upon Campaign registration. However, something commonly overlooked is the fact that The Campaign Registry is simply a registration database that contains information for entities (such as mobile operators, DCA’s, CNP’s, and CSP’s) to reference.

What this means is that the information your customers provide in their Campaign registration will need to be validated and vetted. Since you can realistically input anything in a Campaign registration, it’s not only our duty (and the DCA’s duty) to ensure that each and every registration follows CTIA guidelines, but it is the duty of you as the ISV (Independent Software Vendor) to vet your own customers and the information they provide for the registrations.

You should know that our DCA is pretty strict with what they will and won’t allow on their platform. Their vetting practices are thorough, and we recommend that you take a look at our guide for Upstream Campaign Vetting. We also suggest reviewing our list of Explicitly Prohibited Content to ensure your customers’ use cases will be able to send messages through our platform.

DCA election can take an additional 24 hours or more after you initially connect your Campaign to your SignalWire Space. The sooner you load your Campaign into your Space, the better. SignalWire will not request DCA election until after we have been alerted that a new Campaign needs to be connected, and the Campaign has been loaded into the SignalWire Space.

During DCA election vetting, the DCA will be checking to ensure there is a valid website that showcases who exactly is sending messages, the quality of the registration itself, and if the registration follows CTIA guidelines. Rejections can occur if insufficient information has been provided, and a resubmission fee of $7.50 will be applied upon resubmission.

The Campaign Registry Fees ​

The movement to prevent unwanted messaging content involves a lot of engineering power and is quite costly. This pushes some of the cost down to the individual CSPs, as broken down in the table below. Luckily, SignalWire understands that these fees are enough of a burden for you, and we do not add on any other costs to associate with us. All of these fees will be handled between you and The Campaign Registry.

In addition to TCR’s fees, our DCA (Direct Connect Aggregator, aka companies that provide direct connectivity to mobile carrier gateways for the purpose of delivering messages) has begun charging a $7.50 vetting fee to cover their costs of vetting each new Campaign when they receive a new Campaign connection request. This new vetting process has increased the registration turnaround time to a minimum of 48 hours. Providing insufficient information in the Campaign registration can cause significant delays. If our upstream partner requires additional information, another $7.50 re-vetting fee will be charged with each resubmission. You will be notified if re-vetting applies to your Campaign(s).

We suggest that sufficient information is provided when registering your Campaign(s). This includes a FULL, formal description, up to 5 messaging templates, and if registering directly through SignalWire, a full description of the subscriber opt-in/opt-out process.

Unique Use Cases ​

Not all Messaging use cases are as cookie-cutter as The Campaign Registry would like them to be. That is alright; there are avenues created to address this.

If your campaign cannot be accurately placed in any specific use case, there are two solutions to allow unique use cases through either a Mixed use case or a Low Volume Mixed use case. The low volume mixed use case only costs $1.50 per month. It works great if you do not exceed 15,000 messages/ month and do not exceed 75 transactions per minute.

Organizing your Brands and Campaigns is not always as simple as it seems, that is where we come in to help.

If you ever have any questions about how to register or simplify this process, please reach out to the SignalWire Support Team by creating a support ticket using the ? icon in the top right of your account’s Dashboard.

Additionally, you can also join our Community Discord to pose questions to SignalWire (or to the community of users) and stay updated on all the changes in the telecommunications world!

Registration ​

For AI agents: a documentation index is available at the root level at /llms.txt. Append /llms.txt to any URL for a page-level index, or .md for the markdown version of any page.

Do you need to register with The Campaign Registry? If you are using your SignalWire 10DLC phone numbers to send messages to US numbers, the answer is yes. Here’s how you’ll do it:

  1. Add a payment method if you do not already have one set for your project.
  2. Create a Brand. Make sure your information is correct. Each submission incurs a $4 charge.
  3. Register a Campaign. Include as much detail as possible. There is a monthly fee for each Campaign that varies by use case. You will be charged the monthly fee for the first 3 months up front (as there is a 3 month minimum commitment), and you will not be charged again until the 4th month your Campaign is in use.
  4. Assign Phone Numbers to your Campaign. For a brand new campaign, this process can take up to 24 hours, so do not be alarmed if you see a “failed” or “pending” status for a number in that time period.

If you indicate an interest in messaging when signing up for a SignalWire Space, you will walk through all of these steps in the Campaign Registry sign-up wizard. If you did not already complete the wizard steps, read on for how to use the Messaging Campaigns Space to complete your registration.

Overview ​

Using 10DLC (10-digit long code) numbers for messaging requires mandatory registration with The Campaign Registry (TCR). This process ensures compliance and helps combat spam, benefiting customers, businesses, and the mobile industry. SignalWire, as a registered Campaign Service Provider (CSP), simplifies this registration for you.

The usage of 10DLC for messaging campaigns has increased due to their simplicity and ability to meet application-to-person (A2P) messaging needs between businesses and customers. SignalWire has built powerful messaging APIs to meet these needs. However, the rise in spam texts has led to the creation of TCR to record and validate the sender and content of 10DLC messages.

Anyone using an application platform (e.g., SignalWire) to send messages from a local phone number must register with TCR, regardless of use case. Even if your traffic is mostly person-to-person (P2P), it is likely still considered A2P if sent from SignalWire. If you believe your traffic meets P2P guidelines, please contact our Sales team for further guidance.

Registration process ​

Registration with TCR is required before you can use 10DLC numbers for messaging.

  1. Brands: Register your business to receive a unique Brand ID linked to all campaigns and messages. Required information includes:
    • Company name
    • Website
    • Tax ID/EIN
    • Contact name
    • Direct number
    • Email
  2. Campaigns: Register each messaging campaign with a unique ID. Required details include:
    • Use case
    • Opt-in/out process
    • Message samples

The registration process will take approximately 3-5 business days, though can take shorter or longer depending on the information submitted.

Types of Registration ​

When registering your Brand and Campaigns, you will need to choose between two different types of registration.

  1. Managed Brands & Campaigns: When registering a managed Brand or Campaign, SignalWire acts as the Campaign Service Provider (CSP) and will handle all the registration details with The Campaign Registry (TCR). This is the default option when you submit a registration for a Brand or Campaign. The rest of this guide will be written from the Managed Brands & Campaigns option in perspective.

  2. Self-registered: If you are already registered with TCR and have a CSP ID, you can choose to self-register your Brand or Campaign. This option is available for existing TCR customers who have already completed the registration process with TCR and have a CSP ID. To learn more about what a CSP is, and how to get a self-registered CSP ID, see the CSP Registration Guide.

Brands ​

A Brand is an overall project with which TCR will associate a set of campaigns, numbers, and messages. In this tab, you will see your current Brands and their status. The status will either be Pending if it is still being reviewed or Completed if the review is complete and you are ready to add campaigns.

Details of an existing brand ​

Existing Brand details can also be viewed by using the Retrieve a Brand Campaign Registry API endpoint.

To see the details of an existing Brand, click on the Brand Name. None of these details are editable. If you are trying to make changes to an existing Brand, please use the button to contact Support for assistance.

Brand details page

Creating a new brand ​

New Brands can also be created by using the Create a Brand Campaign Registry API endpoint.

To create a new Brand, start by clicking the blue ”+ New” button to open the New Brand wizard with two options.

  1. Import a Brand that has already been approved by TCR through a different Campaign Service Provider (CSP) by clicking the “Create a Partner Brand” button.
  2. Create a new Brand to register and manage with SignalWire by filling out the form.

Brand creation page

For new Brands, all of the fields on the details page are required by The Campaign Registry. Be careful with your information input, because you do not want to be flagged by TCR for a Brand information error.

Each Brand should have a unique EIN, or you will risk damaging your trust score. After completing the three Brand creation steps, you will see a success message.

Brand creation success page

TCR will check all of your information against multiple databases and return a status of Verified or Unverified. Brand details can only be edited and resubmitted for a Brand in an Unverified status. Your Campaign Registration Specialist will assist you if resubmission is required.

Each submission incurs a $4 charge.

Campaigns ​

Messaging Campaigns page

After your Brand is verified, you can add Campaigns. The simplest way to describe a Campaign is a unique use case. For example, if you send marketing messages and also send two-factor authentication messages, that would represent two different use cases and, therefore, two different Campaigns. Some businesses will require only one Campaign while others may require many. There are also mixed-use cases available for businesses that aren’t worried about throughput.

For a full list of use case descriptions, see our Campaign Registry guide.

Details of an existing campaign ​

Existing Campaign details can also be viewed by using the Retrieve a Campaign Campaign Registry API endpoint.

To see the details of an existing Campaign, click on the Campaign Name. None of these details are editable. If you are trying to make changes to an existing Campaign, please use the button to contact Support for assistance.

Campaign details page

Creating a Campaign ​

New Campaigns can also be created by using the Create a Campaign Campaign Registry API endpoint.

Information required for each Campaign will be your Campaign’s use cases, opt-in/out process, and message samples. Begin by clicking the blue ”+ New” button on the top right of your Campaigns page.

Campaign registration form

Continue through five steps to submit your new Campaign.

Fill in the fields with as much detail as possible. Submitting incomplete or inaccurate information could add processing time and require resubmission with additional fees. When you reach the last step, please take note of the submission fees before submitting. You will see the success screen when you have completed this process.

Once registered, each campaign will be given a unique ID which will be registered directly with the MNO’s. Processing may take 3-5 days. During that time, the status for the Campaign in your Campaigns tab will be Pending.

After a Campaign has been approved, you will see them listed under this Campaigns tab. If you click on the Campaign name, you will see the Campaign details, phone numbers assigned to the Campaign, and an Assignment Orders tab to add new numbers to the Campaign.

Campaign details page

You can assign phone numbers to your Campaign while the registration is still pending, but they can not be put to use until the registration process is complete with both The Campaign Registry and our upstream DCA partners who provide the connection between your sent messages and the carriers.

Campaign Phone Numbers ​

The last step to setting up messaging is assigning your SignalWire phone numbers to a Campaign. The Campaign Phone Numbers tab displays a list of all of the numbers assigned to any Campaign.

As of December 2025, newly purchased US 10DLC numbers do not have messaging enabled by default. When you assign a phone number to an approved Campaign, messaging capabilities are automatically enabled on that number.

For inbound-only use cases (receiving messages without sending), contact Support to request messaging enablement without a TCR campaign.

Campaign phone numbers page

From here, you can click on multiple links to manage your Campaign number details:

  • Clicking on a specific phone number will take you to that number’s details page where you can set up incoming message handling.
  • Clicking on a Brand will take you to that Brand’s details page.
  • Clicking on a Campaign will take you to that Campaign’s details page.
  • The ⋯ button will give you a menu to go to the phone number’s details page or delete the number from its associated campaign.

Phone Numbers can also be assigned to a Campaign by using the Assign a Phone Number to a Campaign Campaign Registry API endpoint.

There are two different places to add a number to a Campaign. Click the blue ”+ New” button on either this Campaign Phone Numbers tab or from the Campaigndetails page you can create a new assignment order in the Assignment Orderstab.

Assign phone numbers page

Whichever method you use, when you create a phone number assignment for a brand new Campaign, SignalWire has to send information up to our carriers to get it connected on their end. For a brand new campaign, this process can take up to 24 hours in normal circumstances. You may see Failed or Pending as the number assignment order status during this time. Rest assured that as soon as it’s completed on the carrier end, you will see it reflected in your portal as a Processed status!

You may have multiple numbers on each Campaign, as long as you have a valid use case for doing so. The maximum is 49 numbers currently. Any more than that will require additional registration for Number Pooling. If this applies to you, open a Support Ticket, and we will discuss this in more detail with you!

Brand details page

Brand creation page

Brand creation success page

Messaging Campaigns page

Campaign details page

Campaign registration form

Campaign details page

Campaign phone numbers page

Assign phone numbers page

Character limits ​

For AI agents: a documentation index is available at the root level at /llms.txt. Append /llms.txt to any URL for a page-level index, or .md for the markdown version of any page.

What is a Message Segment? ​

A message segment is a part of an entire message that has been broken down into several pieces. If the body of the message is larger than 160 GSM-7 characters or 70 UCS-2 characters, it will automatically be broken up into smaller messages and annotated to attempt proper reconstruction on the recipient handset. Not all carriers and handsets support this. You can have a maximum of 1600 characters in an SMS body.

SignalWire will recombine inbound messages into a single message. Your project will be charged for each segment sent or received.

  • All white spaces (space, tab, carriage return) count as a single character toward the total.
  • \r = CR (Carriage Return) → Used as a new line character in Mac OS before X
  • \n = LF (Line Feed) → Used as a new line character in Unix/Mac OS X
  • \r\n = CR + LF → Used as a new line character in Windows

Never copy and paste the message content that you are going to send! Doing so is likely to result in segmenting and delivery issues.

View Message Encoding ​

Check your SignalWire Space portal for the full breakdown to see how your messages are encoded and sent. Click an individual message record to see the encoding details, cost, character count, number of segments, and number of media attachments.

A message record in a SignalWire Space portal titled 'Message Encoding Details' The message is split into three parts, labeled 'Segments 1 through 3'. Each character of the message is in a square box. The first three boxes of each segment are colored blue, and show the code 'UDH'. Emojis are shown in pink boxes.

GSM ​

When all characters in an SMS are part of the GSM 7-bit alphabet, the SMS is billed as GSM. This allows for up to 160 characters in a single message segment.

For larger messages beyond 160 characters, all segments (including the first) will be segmented at 153 characters per segment, using 7 characters for each segment’s User Data Header. These are industry standards ensuring proper assembly/disassembly of SMS amongst various handsets.

Unicode ​

A single Unicode character such as (♥) causes the entire message to be billed as Unicode. This allows for up to 70 characters in a single message segment.

For larger messages beyond 70 characters, all segments (including the first) will be segmented at 67 characters per segment, using 3 characters per segment’s User Data Header.

Final Note about Carriers ​

Some carriers may not utilize all 5 segments in an SMS and may limit to 5 or fewer. That decision is carrier-dependent and does not reflect SignalWire’s ability to send up to 5 segments.

If a message is being truncated, you can always create a support ticket with a Message SID of the truncated message, and we can reach out to our carrier peer to see if there were any issues in delivery. However, they will often advise that the decision is based on the end user’s carrier and therefore, that user would need to inquire with their carrier to find out more.

Hosted messaging ​

For AI agents: a documentation index is available at the root level at /llms.txt. Append /llms.txt to any URL for a page-level index, or .md for the markdown version of any page.

Hosted Messaging allows you to use SignalWire to send and receive SMS and MMS on 10DLC and Toll-Free VoIP phone numbers that are held elsewhere for voice (such as a PBX or VoIP provider).

Use Hosted Messaging to migrate a phone number to SignalWire’s robust Messaging platform while maintaining your existing Voice infrastructure.

Prerequisites ​

  • A Letter of Authorization (LOA) signed and dated by the authorized user or administrator of the number within the past 30 days

    • Download the LOA form from the “Letter of Authorization” section of the Port In form

  • A recent invoice from the current voice provider showing the phone number in service

  • Permission from your current voice provider to split Messaging services away from Voice services

  • An active Campaign with The Campaign Registry(not required for Toll-Free numbers)

    • Valid 10DLC Campaign provisioning is required for all US VoIP phone numbers to send outbound messages to the US.
    • Please ensure that your 10DLC Campaign is in an active state with SignalWire before requesting to host your messaging services.
    • Learn more about The Campaign Registry

SignalWire does not offer Hosted Messaging services for mobile (wireless) phone numbers. You can convert a wireless number to VoIP (non-wireless) by porting both Voice and Messaging services to SignalWire.

Instructions ​

1

Verify ownership ​

Before SignalWire can host messaging, we must verify that you have ownership and authorization to text enable the phone number(s).

To do so, complete a Letter of Authorization.

Letter of Authorization form\ \ Download the LOA form under the section titled “Letter of Authorization”.

2

Complete request form ​

Click Initiate Port Request to complete the form in your SignalWire Dashboard in the Port Requests area of the Phone Numbers section. Fill out all required fields. Under Services to Port, be sure to select Messaging Services Only.

Port Requests\ \ Open the Port Requests interface in your SignalWire Dashboard.

Standard Hosted Messaging requests submitted outside of the process outlined in this guide will not be processed, and you will be instructed to return to your Dashboard to submit the order properly. SignalWire does not currently offer an API for porting submissions.

3

Order processing and configuration ​

Once your request is received:

  1. SignalWire will review the documentation provided and will add the phone number to your account.
  2. SignalWire will submit the order to host messaging services. There is a 48 hour minimum turnaround time for message enablement processing. During this time, messaging services should still process through the voice provider or current messaging service provider.
  3. Once the phone numbers are added to your dashboard, set up your Inbound Message Settings in the phone number configuration. You won’t be able to test right away, as the hosted messaging request is still processing.
  4. 10DLC Campaign provisioning (for US numbers only) begins once the Messaging services have been enabled. This process may take 10-30 minutes. During this provisioning step, outbound messaging will not function.

4

Hosted Messaging active ​

Once SignalWire confirms message enablement, test inbound and outbound functionality.

With all of the above steps completed, you’re ready to go!

Next steps ​

Keep Voice services active ​

You must keep Voice services active with the current voice provider in order to host messaging services with SignalWire.

Releasing the phone number with your old voice provider could result in disruption of messaging services. If you wish to port the number completely away from your old provider, follow our guide to porting both voice and messaging services.

Registration or Verification requirements ​

10DLC (local) numbers

Maintain valid 10DLC Campaign provisioning. Consult our reference to 10DLC Campaigns and our documentation on The Campaign Registry for more information.

Toll-Free numbers

To begin messaging, follow the required Toll-Free verification process.

Frequently asked questions ​

Can I release Voice services from my old provider once SignalWire's Hosted Messaging is active? ​

No. If you release Voice services, you will release the whole number. This will break Hosted Messaging.

Is there an API for port requests? ​

Not currently.

Support ​

If you have any questions or need assistance during the porting process, contact Support. Ensuring a smooth and timely transition is our top priority, and we’re happy to guide you through each step.

MIME types ​

For AI agents: a documentation index is available at the root level at /llms.txt. Append /llms.txt to any URL for a page-level index, or .md for the markdown version of any page.

To send MMS, you must include a media attachment. The content-type header must have an accepted content type, or SignalWire will have to reject the request.

Media Size Limits ​

The overall size limit is 1.2MB for local numbers and 750KB for toll-free numbers. Most carriers support message attachments with a total size of 1MB-1.2MB. However, to maximize deliverability across all carriers, limit your attachment size to 500KB.

Accepted MIME Types ​

All of the following MIME types are accepted. SignalWire will not modify the body content for device compatibility.

TypeDescription
audio/mp4mpeg layer 4 audio
audio/mpegmpeg layer 3 audio
audio/mpeg3mpeg layer 3 audio
audio/oggogg audio
audio/vorbisaudio compression format
audio/vnd.wavwav format audio
audio/ac3codec format audio
audio/amrcodec format audio
audio/midimusical instrument digital interface format
image/jpegjpeg format image
image/gifgraphics interchange format
image/pngportable network graphics format
image/bmpbitmap image format
text/plaintext file format
text/calendartext file format
text/vcardtext file format
text/x-vcardtext file format
video/mpegmpeg video format
video/mp4mpeg layer 4 video format
video/quicktimequicktime video
video/h264video compression format
video/3gpmedia container format

Platform Free Trial ​

For AI agents: a documentation index is available at the root level at /llms.txt. Append /llms.txt to any URL for a page-level index, or .md for the markdown version of any page.

Platform Free Trial (PFT) provides a way to test SignalWire’s messaging APIs before registering Brands or Campaigns with The Campaign Registry. There is no set length of your trial, so you can take your time experimenting with Messaging. The only cost to you is standard message rates and carrier fees.

It is simple to set up, but, as a trial, it does have restrictions. Let’s go over the details.

Enabling Platform Free Trial ​

1

Verify a personal phone number ​

For users who are completely new to SignalWire, enabling Platform Free Trial is mostly automated with required onboarding information. One of the onboarding steps is to verify a mobile phone number. This is the one and only number that will be able to receive test messages.

Existing users who have not already registered with The Campaign Registry will find a prompt in the Messaging Campaigns page of the Dashboard to enable Platform Free Trial by verifying a new phone number.

A previously verified phone number will not be automatically enabled for PFT. If you would like to enable PFT test messaging with a previously verified number, remove the number and re-verify it to trigger PFT set-up.

You will see an icon in your verified Caller ID list marking which number is enabled for test messaging.

2

Purchase a SignalWire phone number ​

The second step to enabling Platform Free Trial is to purchase a SignalWire phone number. For new users, the first number you purchase will be PFT enabled. For existing users with previously purchased phone numbers, SignalWire will assign one of your numbers to be PFT enabled as soon as you have verified a mobile number. This number is usually the most recently purchased.

When you have a verified mobile number and an active SignalWire number in your account, you will see a notice in your Messaging Campaigns Space that you can now send test messages.

For a quick start on sending your first message, see the Try it out examples on the Messaging overview.

Trial Restrictions ​

Test messages with Platform Free Trial may only be sent from the assigned SignalWire phone number to the assigned verified mobile number. No other messaging traffic will be possible without registering a Campaign with The Campaign Registry.

There is a limit of 200 messages per day.

SMS integrations with LaML, SWML and Call Flow Builder will not work with Platform Free Trial.

Each message is prepended with [SignalWire Free Trial].

PFT is a single-use trial ​

Releasing or removing either your PFT-enabled SignalWire phone number or verified caller ID number will end the free trial. You will not be able to re-enable the trial by adding a new phone number. You would be unable to send any further messages until registering a Campaign with The Campaign Registry.

Optimize delivery rates ​

For AI agents: a documentation index is available at the root level at /llms.txt. Append /llms.txt to any URL for a page-level index, or .md for the markdown version of any page.

The best way to ensure that your messages reach their intended audience is to follow these rules.

Not surprisingly, the best way to avoid being flagged as spam is to ensure that your customers want to receive your messaging.

Every time you send out a messaging campaign, you should have accurate, reliable, verifiable recipient opt-in information that is specific to the type of messaging that you are sending. For example, just because a customer opted in to receive account notifications does not mean that they have consented to receive new product marketing. When you follow this opt-in strategy, generally opt-out rates are consistently low (less than 5%) due to obtaining clear recipient consent.

According to the Cellular Telecommunications and Internet Association (CTIA) guidelines, you should also make sure that as soon as a recipient opts in, you send them an opt-in confirmation message.

The other side of the consent coin is of course opting out. It is absolutely essential to offer your customers a way to opt out in every message, even though they already opted in.

Customers have the right to change their minds about receiving future messages at any time for any reason. Providers who offer messaging services have an obligation to process the opted-out consumer phone number so it is removed from all distribution lists and logged as “opted out” from SMS communications. This ensures that future messages are not attempted and consumer consent is honored.

There are many different methods of including opt-out messaging in your message body. This could include “Reply STOP to opt out”, “Reply NO to cancel”, “Send X to opt out”, or even versions in other languages such as “Responde NO para cancelar.”

Number Association ​

Phone numbers should be associated with a single use case. Using the same numbers for multiple different increases the chance of issues, so it’s best to not cross-pollinate campaigns.

If the numbers are meant for the same brand, can you use the same set in that case? No. Maybe you own a car repair service - you would not want to use the same numbers for marketing purposes that you would for appointment confirmations. This is much more likely to make the carriers question whether your traffic may be illegitimate. Identify sets of numbers for each of your various use cases, and keep them on separate tasks.

Brand Identification ​

It is vitally important to include your service or business name in the content of the body. Including this information is helpful to both the customers and the carriers.

Example Message: “Your appointment is at 3”.

What if you made your dentist appointment 6 months ago at your last cleaning, and you totally forgot about it? You might assume this message isn’t for you and ignore it entirely. So how can we make that better?

Example Message Improved: “Dr. Crentist’s Office: Hello Dwight. Your dental cleaning and crown fitting with Dr. Crentist is scheduled for 3 PM on Jan 1st, 2022. Call our office to cancel or reschedule. Reply STOP to opt out.”

This is much more clear and makes it obvious to both the customer and the carrier that this is a simple customer requested appointment reminder.

Shortened URLs ​

Shortened URLs can often cause issues as carriers can view them as likely to be spam. If you need to use a link in your message, the full domain is always preferred. If you must use a shortened URL to deliver a customer link, make sure that it is not a common, public, or shared domain shortener. You must use a shortener with a web address and IP address(es) dedicated to your exclusive use.

Here is a list of common public URL shorteners that will result in your messages being flagged as spam:

  1. bit.ly
  2. goo.gl
  3. tinyurl.com
  4. Tiny.cc
  5. lc.chat
  6. is.gd
  7. soo.gd
  8. s2r.co
  9. budurl.com
  10. bc.vc

To avoid public URL shorteners, consider using a private URL shortener with a domain and IP dedicated to your exclusive use.

Explicitly Prohibited Content ​

Some content is explicitly disallowed from being sent via SMS/MMS with SignalWire.

  1. Social marketing
  2. Collections
  3. Financial services, whether account notifications, marketing, collections or billing for:
    • High-risk/subprime lending/credit card companies
    • Auto loans
    • Mortgages
    • Payday loans
    • Short-term loans
    • Student loans
    • Debt consolidation/reduction/forgiveness
  4. Third Party Insurance
    • Car Insurance
    • Health Insurance
  5. Gambling, Casino, and Bingo
  6. Gift cards
  7. Sweepstakes
  8. Free prizes
  9. Investment opportunities
  10. Lead generation
  11. Recruiting
  12. Commission programs
  13. Credit repair
  14. Tax relief
  15. Illicit or illegal substances
  16. Work from home
  17. Get rich quick
  18. UGGS and Rayban campaigns
  19. Phishing
  20. Fraud or scams
  21. Cannabis
  22. Deceptive marketing
  23. SHAFT: Sex, Hate, Alcohol, Firearms or Tobacco
  24. Miscellaneous shams, schemes, hoodwinks, and bamboozles

Including prohibited content in your messages can get your account flagged for fraud. Repeat or serious offenses can result in suspension or cancellation of your SignalWire services.

What to do if you are flagged as spam? ​

FIRST, make sure that you are following all of the rules described above. Are you using opt-in/opt-outs, declaring your brand, ensuring full domain URLs, and not including any prohibited content?

SECOND, if you’re sending from local numbers, are you already registered with The Campaign Registry? If not, you can read our guide to The Campaign Registry.

THIRD, if you already have a registered campaign, are you using numbers that are registered to a campaign and sending the content that was approved for the campaign?

IF you are following all of these rules and still being flagged as spam, it’s time to engage our excellent support team. Create a Support Ticket and include the message SID of a message that was marked as spam so that our team can investigate the cause.

Why use SMS marketing? ​

Integrating SMS into your marketing strategy creates much more meaningful interactions with customers. SMS marketing boasts an unbelievably high open rate of 98% with 45% of people responding to these messages. To compare, successful email campaigns only reach open rates of 20%-40% and cold calls average 2%.

Consumers in this day and age spend an average of 3.3 hours on their phones, and most smartphone users check their phone at least once every 10 minutes. With that in mind, it’s easy to see how much more accessible SMS marketing is compared to many other strategies.

Even though it’s been proven that SMS as marketing is very effective, many businesses are still behind the trend, making it the perfect time to start deploying SMS as a strategy. Jumping on this trend while it’s still fresh shows your customers that you’re able to keep up with the demands of modern communication.

SMS marketing is also much quicker to execute as you don’t have to spend hours creating email templates or writing ad copies/long-form content. You can write a short simple text in a matter of minutes and begin sending out your campaign.

What industries are best suited for SMS campaigns? ​

Marketing

  1. Special Deals and offers
  2. Exclusive Content

Political Messaging

  1. Polls
  2. Voting Information
  3. Campaign Updates

Appointment Reminders and Updates

  1. Opt-in to receive notifications when an appointment is coming up
  2. Ride share notifications
  3. Food delivery updates

And many more!

  1. Breaking news, Telehealth, birthday deals, etc.
  2. City Wide Announcements or Emergency Updates
  3. Hair salons and spas
  4. Electricians, plumbers, roof repair

How to avoid customers viewing your messages as spam? ​

Again, the number 1 priority is to make sure your customers WANT your messages.

You can also list your company’s number on your website and give it out at promotional events such as conferences or networking events. This can help make sure your number is easily associated with your brand.

You can help encourage people to text your number by offering incentives such as monthly deals or exclusive updates.

Lastly, even though your customers have opted in, it’s best not to send them more than 4 texts a month. No one wants to get tons of repetitive marketing messages which can lead to the opposite effect and cause customers to lose interest in the product out of annoyance.

Toll-free verification ​

For AI agents: a documentation index is available at the root level at /llms.txt. Append /llms.txt to any URL for a page-level index, or .md for the markdown version of any page.

Overview ​

Toll-free numbers are a great alternative to messaging with Short Code or 10DLC (local area code) numbers. In the US, toll-free numbers can be used for business messaging to all major US carriers, as well as most major mobile Canadian carriers.

All toll-free numbers must be verified prior to sending messages.

Toll-free verification form\ \ Submit this form to begin the verification process for a new toll-free number.

As a rule of thumb, some categories of messaging are forbidden on SignalWire. Please take the time to review our list of explicitly prohibited content before submitting your application for Toll-Free, 10DLC, and Short Code.

Downstream message filtering is designed to prevent unwanted messaging, fraud, and abuse. Before considering verifying your Toll-Free number, please be sure to follow the CTIA guidelines and best messaging practices.

Requirements ​

The following standards must be followed for Toll-Free messaging:

  • Obtain clear opt-in consent from your recipients before sending messages
  • Enable easy opt-out for message recipients
  • Avoid using shortened URLs
    • It’s highly recommended to use a full branded URL as well as URLs that lead back to a legitimate website that contains branding, a privacy policy, terms of service, and contact information. Publicly hosted URL shorteners are forbidden and are guaranteed to cause spam blocks.
  • Using multiple Toll-Free numbers to send the same or similar content to bypass throughput limitations is known as snowshoeing. This is highly prohibited by carriers. If you need to increase your throughput, it can be approved by our Sales team. If you have a valid use case for using multiple Toll-Free numbers (such as multiple locations all requiring an individual Toll-Free number), this is something we may be able to work out with our carriers.

Verification process ​

Getting your Toll-Free number verified means that your business and use case has been reviewed and vetted prior to sending messaging via Toll-Free and that your content has received carrier approval.

There is no charge associated with the verification process.

Having your Toll-Free numbers verified will greatly reduce the risk of spam filtering on Toll-Free traffic towards all major mobile carriers in the US, as well as most major mobile carriers in Canada. Make sure you stick to the content you submitted for verification and continue to follow SignalWire’s messaging best practices and code of conduct. Deviation from your verification registration can still result in spam filtering. Verified does not mean whitelisted.

Verification affects messaging to mobile subscribers in the United States as well as Fido, Rogers, Telus, and Videotron in Canada.

Note: Other (non-US/Canada) countries do not treat Toll-Free SMS any differently than other international SMS, and you should consult that country’s SMS Guidelines page to learn more about compliance considerations for messaging.

Toll-Free Verification Process ​

If you believe you have a valid use case for a Toll-Free number, our Carrier Operations team would be happy to assist you. Once you fill out the verification form, a ticket will be generated for our Carrier Operations team to process. The turnaround for Toll-Free verification is 3-5 business days.

Due to an influx of upstream requests, our messaging peer has stated that the current turnaround time for registrations can be around 1-2 weeks or longer if insufficient information is provided.

The form linked above includes the following fields, all of which are required.

FieldDescription
Business NameLegal name of business
Company WebsiteOfficial company website
Business AddressPrimary physical address of business
Compliance ContactSomeone at your business who can respond to compliance questions if they arise)
Requested ThroughputDefault is 3 MPS
Toll-Free number(s) to be verifiedIf multiple, please provide justification.
Use CaseDescription of the Use Case
Message ContentSample messages that reflect the type of content you will be sending.<br>Samples need not include every possible iteration of your messaging content, but they should represent the majority of planned content.
Opt-in DescriptionDescribe how your recipients provide consent to receive messages.
Opt-in detailsLink to, image of, or scanned copy of opt-in page or process
Business Registration NumberA unique identifier assigned to a business by a government authority or regulatory agency to identify and legitimize the business is recognized and allow to operate within a specific jurisdiction.
Issuing Country of Business RegistrationThe country where the business is legally registered to operate.
Entity TypeThe classification of the business based on ownership and purpose based on the following:<br>- Public Profit<br>- Private Profit<br>- Non-Profit<br>- Government<br>- Sole Proprietor (requires additional vetting)

Effective September 30th, 2025, the Business Registration Number, Issuing Country of Business Registration, and Entity Type fields will be added to the existing Toll-Free Messaging Verification Form. These fields will be optional until January 1st, 2026 at which time they will be mandatory.

FAQs ​

I have many Toll-Free customers under my account, can I verify in bulk? ​

If you are an ISV, for example, and need to complete verification for multiple customers/multiple numbers, please download this template and fill out the required information for each number. To download, click File > Download > Microsoft Excel (.xlsx). Once you’re ready to submit, send the form to support@signalwire.com and our Carrier Operations team will be in touch.

Is there an API available? ​

No.

Does TCR (The Campaign Registry) process toll-free verifications? ​

No, TCR is not involved with Toll-Free verifications. A specific Toll-Free Aggregator handles Toll-Free messaging for the industry and is unrelated to TCR.

Why does Canada have stricter requirements? ​

Canada is more restrictive because of its anti-spam laws and the policies implemented by mobile carriers to meet the law.

Toll-Free Verification and the downstream provider require legal language to be found somewhere on the brand’s website about messaging. You will have to provide a link to your company’s terms and conditions and your privacy policy.

How long does the toll-free verification process take? ​

It can take up to 2 weeks, from start to finish.

If my Toll-Free number is verified, does that guarantee deliverability? ​

No, your verified Toll-Free number is subject to limited filtering. If your content is flagged as spam, that specific content will be blocked, but not the Toll-Free number.

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