AT&T messaging requirements




As of Wednesday, September 30th, 2020, AT&T may increase their blocking of messages, including political messaging, and/or associated phone numbers sending messages to AT&T subscribers. These guidelines apply to all messaging channels, including 10DLC/Local A2P, toll-free, and short code.

Types of messages subject to being blocked:

  • Fail to use opt-out notices (e.g., "reply STOP 2 end") in all subscribed messages.
  • Include public URL shorteners.
  • Use spam filter evasion techniques, such as rapidly changing URLs or use of unnecessarily large pools of sending numbers.

If you're a Bandwidth customer sending messages to AT&T subscribers, you're encouraged to ensure your messages meet the guidelines put forward by AT&T in order to reduce any risk of blocking by AT&T. Please review our Messaging Deliverability Guide for recommended best practices.

I'm only sending a single message without signing recipients up for ongoing ones. Do I need to add an opt-out notice?

No, if only a single message is sent (for example, a one-time two-factor authentication code), this is not required.

Note: When using a toll-free sending number, “stop” responses will opt recipients out of being able to receive messages from that sending number regardless of the nature of the campaign.

What is a public URL shortener?

These are domains set up by services like or tiny.url that can be used by multiple different businesses.  We recommend that you obtain your own dedicated domain if you need shortened links for your messaging campaign.

Will opt-out language count towards the character count limits for SMS?

Yes, the character limit of 160 (or 70 for USC-2 encoding) is a technical limit throughout the messaging ecosystem. Messages above 160 characters will be split into multiple billable segments. 

Until there's a full carrier local A2P solution, there are rate limitations that require me to use multiple sending numbers. Will I be blocked?

Bandwidth's Messaging Terms and Conditions state that customers must not "send SMS messages from more source TNs, TFNs and/or Short Codes than reasonably necessary to support the functioning of Customer’s application(s) (also known as “snowshoeing”)." That remains our policy, however we understand that without a full carrier A2P messaging solution for local numbers it can be difficult for you to manage sending rates when you have a need to utilize local numbers.

As long as you're only using as many sending numbers as is reasonably needed based on the current environment and MPS restrictions, and not flagrantly cycling or pooling numbers in a way that would indicate a primary goal of avoiding carrier filtering, that's in line with Bandwidth policy and AT&T’s guidance. There's no hard number or threshold, please use your reasonable judgment. As local A2P solutions become fuller and there's no longer any reasonable need to utilize many different sending numbers, expectations should adjust accordingly.

Will other carriers follow AT&T?

It's likely that other carriers in the industry will issue guidances similar to AT&T, but for now, none of them have made an official statement.

Can you review/whitelist my campaign?

No. We recommend reviewing Bandwidth’s messaging best practice guides. We can't guarantee delivery, but we can give a message the best shot of delivery, as well as advocate for them downstream if they follow all the best practices. 

My messages are being blocked. What should I do?

Please open a ticket with your Bandwidth Support Team and provide the following information:

  • Messaging details
  • From
  • To
  • Message ID
  • Date and Time
  • Campaign details
  • Phone Number Sending Traffic
  • Volume (if available)
  • Content Being Blocked
  • Use Case
  • Process to Opt-in
  • Website or any online information listed by your end-user
  • Privacy Policy
  • Terms of Service

Article is closed for comments.