Note: This article helps you follow best practices for A2P messaging. It doesn't constitute legal advice. All messaging traffic must comply with relevant laws and regulations, including the Telephone Consumer Protection Act (TCPA).

Make sure consumers explicitly say they want messages from you.

Reliable consumer opt-in is the most important practice on this list. Your opt-in must match the type of messages you send. When consent is clear, opt-out rates stay consistently low.

Bandwidth or wireless carriers can ask you (or your customers) for proof of documented opt-in consent for any message, at any time.

Carriers watch opt-out rates closely. The daily opt-out rate for a campaign or number triggers these actions:

The daily opt-out rate is the number of unique consumers who opted out, divided by the number of unique consumers you messaged in a 24-hour period.
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Use a single number for your identity.

Don't spread a campaign across several numbers. A single number for both text and voice also gives consumers a better experience.

Avoid spreading messages across many source numbers to dilute reputation metrics or evade filters. This practice is called "snowshoeing," and it can get your content blocked.

If your use case needs multiple numbers to distribute similar content, talk to your Bandwidth representative (or your other carrier representative) first.
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Include your application, service, or business name in the message body.

[Your Business Name]: You have an appointment for Tuesday 3:00 p.m., reply YES to confirm, NO to reschedule. Reply STOP to unsubscribe.
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Tell consumers they're opted in.

After a consumer successfully opts in, send a confirmation message to their number right away. CTIA's Messaging Principles and Best Practices call for a single confirmation that verifies enrollment in the program and explains how to opt out.

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 repeating your opt-in confirmation or HELP message once a month or every six messages. Consumers then always know how to opt out and how to reach you.
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Make sure consumers can opt out.

Tell consumers they can opt out of future messages. This matters most for informational and promotional messages.

Add a line such as "Reply STOP to unsubscribe" or "Reply STOP to cancel" to the end of your initial message. Put the word "reply" before the STOP keyword.

Make sure opt-out behavior works as intended.

On toll-free SMS, the network enforces opt-in and opt-out through the STOP and UNSTOP keywords. You can't disable this behavior for service providers or message senders.

On all channels, you still have obligations when a consumer opts out:

Keep a log of STOP responses, and watch for rising opt-out percentages.

Valid opt-out keywords include "STOP," "Stop," "stop," "ARRET," "Arret," and "arret."

On toll-free SMS, you don't need to send an acknowledgment. Your network provider (like Bandwidth) returns a generic confirmation that explains how to opt back in:

NETWORK MSG: You replied with the word "STOP" which blocks all texts sent from this number. Text back "UNSTOP" to receive messages again.
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Let consumers opt back in after a network-level opt-out.

A consumer can opt back in at any time by texting "UNSTOP" or "START" to your number. The keyword isn't case sensitive. It triggers an opt-in only when it's the entire message, with no punctuation or leading spaces. The network trims trailing spaces. A keyword inside a sentence doesn't trigger an opt-in.

Valid opt-in keywords include "UNSTOP," "Unstop," "unstop," "START," "Start," "start," "DEBUTER," "Debuter," and "debuter."

The network returns a generic message that tells the consumer two-way texting has resumed:

NETWORK MSG: You have replied UNSTOP and will begin receiving messages again from this number.
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Give consumers a clear way to learn who you are and how to opt out.

HELP keywords aren't required on toll-free messages, but Bandwidth strongly suggests them. You manage HELP yourself, because the network doesn't process it.

Bandwidth recommends that your HELP response include:

Example: BW Employee Alerts: Help at 844-567-5048. Msg&data rates may apply. Reply STOP to cancel.
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Associate each campaign with a single web domain that you own.

A full domain is preferred. You can use a URL shortener to deliver custom links, but avoid common, public, or shared shorteners, including:

Examples of good URLs:

For more details, read Deliverability and shortened URLs.
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Every registered campaign comes with an approved use case, description, message flow, and set of sample messages. Carriers and aggregators use that registration to decide how to treat your traffic.

Drift happens when your live traffic stops matching what you registered. It comes in two forms that often overlap.

Campaign drift happens when the campaign as a whole no longer matches its registration. Common causes include:

Content drift happens when individual messages stray from the registered use case or sample messages. Industry providers sometimes call this "drift content." Common causes include:

Carriers and aggregators run systems that flag and filter content that doesn't align with a registered campaign type. Some detection compares live messages against the sample messages you registered and flags traffic that strays too far.

Drift can lead to:

Use case also affects fees and throughput, so misaligned traffic can receive the wrong treatment.

Drift also undermines consent. A consumer who opted in to appointment reminders hasn't agreed to receive promotions.
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These signals can point to drift:

In addition to the best practices above, read Canada toll-free messaging best practices.
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CTIA is the trade organization that represents the US wireless communications industry. It maintains resources that help you understand the complex telecom environment and industry guidelines, including:

Open a ticket with your Bandwidth Support team, or call (855) 864-7776.