A2P use case best practices


Luke Thompson


Note: This article is meant to help you follow the best practices for A2P messaging, but it doesn't constitute legal advice. All messaging traffic is required to comply with relevant laws and regulations, including, but not limited to, the Telephone Consumer Protection Act (TCPA).

The following list includes best practices and guidelines for different A2P messaging use cases.




The consumer must give appropriate consent

Make sure users explicitly say they want messages from you.

The single most important practice is ensuring you have accurate, reliable consumer opt-in specific to the type of messages you are sending consumers. Generally, opt-out rates are consistently low when you have obtained reliable and clear consumer opt-in consent. At any time, Bandwidth or wireless carriers may require evidence from you (or your customers) of documented opt-in consent for a particular message.

If opt-out rates exceed 0.5%* in a 24 hour period for a particular campaign or number, you can expect to complete a consent audit to prove that your campaign is in compliance and appropriately collecting opt-in. If a campaign or number receives opt-outs in excess of 4%*, the campaign or number in question may be suspended and an RCA and consent audit will be required.

*The daily opt-out rate is defined as the total number of unique consumer phone numbers divided by the unique opted out consumers that were sent messages in a 24 hour period.

Single number use

Utilize a single number for identity

Don’t spread your campaigns over several numbers.

Using a single number for both text and voice calls is not only a best practice, it’s also a better overall user experience. Avoid spreading messages across many source phone numbers, specifically to dilute reputation metrics and evade filters. This is referred to as “snowshoeing” and can result in your content being blocked. If your messaging use case requires the use of multiple numbers to distribute “similar” or “like” content, please discuss with your Bandwidth rep (or other carrier rep).

Brand identification

Identify the brand or business in the body of the message

Your application, service, or business name should be included in the content of the body.

Example: [Your Business Name]: You have an appointment for Tuesday 3:00PM, reply YES to confirm, NO to reschedule. Reply STOP to unsubscribe.

Opt-in confirmation

Let users know they have been opted in to receive messages from you.

Upon successful opt-in by a mobile subscriber, an opt-in confirmation message will immediately be sent to the mobile subscriber number. Per the CTIA Messaging Principles and Best Practices, “a single opt-in confirmation message displaying information verifying your customer’s enrollment in the identified program and describing how to opt-out” should be sent.

Example: Bandwidth Product Trial Alerts: Welcome to Bandwidth Trial Alerts! Msg&data rates may apply. Recurring Messages. Reply HELP for help, STOP to cancel.

Bandwidth recommends sending your opt-in confirmation message or HELP message (see below) once a month or every 6 messages so customers know how to opt-out and how to reach the business if they have questions.

Support for STOP

Use of Opt-Out language

Make sure your users can opt-out of receiving messages.

The best practice is notifying the consumer of their ability to opt-out from future messages from the message sender. This is especially important when sending informational or promotional messages.

An example would be to include the sentence, “Reply STOP to unsubscribe” to the end of the initial message sent to the consumer, or “reply STOP to cancel”. Best practice is to use the word "reply" before the stop keyword.

Processing STOP keywords

[Only for toll-free A2P]

Ensure proper functioning of opt-out behavior.

On toll-free SMS, consumer opt-in and opt-out functionality is enforced at the network level via the STOP and UNSTOP keywords. This functionality cannot be disabled for service providers or message senders.

On all channels, message senders have obligations to process the opted-out consumer phone number so it is removed from all distribution lists and be logged as “opted out” from SMS communications. This ensures that future messages are not attempted and consumer consent is honored. As you track opt out responses, it is best practice to keep a log of how many STOP responses you receive and monitor for increasing percentages of opt out responses. 

Examples of valid opt-out keywords: “STOP”, “Stop”, “stop”, "ARRET", "Arret", "arret".

For toll-free SMS, there is no need to send an acknowledgment to the consumer. The opt-out confirmation message returned to a consumer is generic from your network provider and gives instructions on how to opt back into service again with the message sender’s phone number. Below is an example of an opt-out confirmation message sent from your network provider (like Bandwidth):

Example: NETWORK MSG: You replied with the word "STOP" which blocks all texts sent from this number. Text back "UNSTOP" to receive messages again.

Processing UNSTOP and START keywords

[Only for toll-free A2P]

Ensure proper functioning of opt-in keywords specific to toll-free texting

Allow users to opt back in after opting out at the network level.

A consumer can opt back in at any time to receive messages by texting the keyword “UNSTOP” or "START" to a message sender’s phone number. The keyword is not case sensitive and triggers an opt-in only when sent as a single word, with no punctuation or leading spaces (any trailing spaces are trimmed). If the consumer uses the opt-in keyword within a sentence an opt-in is not triggered.

Examples of valid opt-in keywords: “UNSTOP”, “Unstop”, “unstop”, "START", "Start", "start", "DEBUTER", "Debuter", "debuter".

The message returned to a consumer is generic and informs the consumer they can start two-way texting with the message sender’s phone number again.

Example: NETWORK MSG: You have replied UNSTOP and will begin receiving messages again from this number.

Processing HELP keywords

HELP commands should present a clear way for the end user to identify information about the message sender and how to opt out if necessary.

HELP keywords are not required on toll-free messages but are strongly suggested. HELP must be managed by the customer – there's no network-level processing of HELP. 

Bandwidth recommends the response to a HELP command includes the following:

  • Business name and description
  • Contact info (TN, TFN, or email) for the business
  • Language about any associated fees or charges
  • Instructions on how to opt-out

Example: BW Employee Alerts: Help at 844-567-5048. Msg&data rates may apply. Reply STOP to cancel.

Single domain

Use a single domain for URLs in your messages

Each campaign should be associated with a single web domain owned by the customer.

Although a full domain is preferred, a URL shortener may be used to deliver custom links. You should avoid the common, public, or shared domain shorteners, such as:

  • bit.ly
  • goo.gl
  • tinyurl.com
  • Tiny.cc
  • lc.chat
  • is.gd
  • soo.gd
  • s2r.co
  • Clicky.me
  • budurl.com
  • bc.vc
  • .xyz

Examples of good URLs:

  • .com
  • .gov
  • .org
  • branded shortened URLs

For more information on URLs, see Deliverability and Shortened URLs.

Canada-specific considerations

In addition to the best practices listed above, see Canada toll-free messaging best practices.

What is CTIA?

CTIA is a trade organization that represents the wireless communications industry in the U.S. They create and maintain lots of great resources, like the CTIA Messaging Principles and Best Practices, to help understand the complex telecom environment and industry guidelines.

You can also check out the CTIA Short Code Monitoring Handbook. Although it's about short codes, the same basic principles and rules apply. 

Questions? Please open a ticket with your Bandwidth Support Team or hit us up at (855) 864-7776!

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