How STOP and Opt-Out Works

Text message opt-out is not something TelBuddy has to build, configure, or turn on: it is enforced automatically by the carrier itself, on every single number, whether it is on Twilio or Telnyx. This happens at the carrier level, below TelBuddy, so it applies even to messages sent completely outside TelBuddy's interface.

What happens when a customer opts out. If someone replies STOP (or a small set of standard variants the carriers recognize), the carrier immediately blocks all future messages from that specific number to that customer and automatically sends them a one-time confirmation that they have been unsubscribed. This is carrier policy, not a TelBuddy setting. It cannot be turned off, and it should not be.

What TelBuddy adds on top of that. Two things, both aimed at making the experience clearer without adding friction to real conversations:

1. An opt-out line ("Reply STOP to unsubscribe") is automatically appended to outbound messages sent to a number that has never texted you, and stops being added as soon as a real conversation exists.
2. If you try to text a customer who has already opted out, you will see a plain-language message explaining that they have opted out, instead of a raw, confusing API error from the carrier.

Getting a customer back after they have opted out. They need to text a keyword like START back to the same number themselves. This is not something you can override or re-enable from your side, again by carrier design, since it is meant to be the customer's own choice.

Why this matters more with Auto Mode on. If AI Auto Mode is active on a number and a customer has opted out, the plain-language block message is what you will see reflected in the inbox rather than a delivery failure. Worth knowing so it does not look like a technical problem when it is actually expected compliance behavior.

Features at a glance

• STOP enforcement happens automatically at the carrier level, on every number
• Applies identically on Twilio and Telnyx
• Opt-out disclaimer added automatically to cold outbound messages, and dropped once a conversation is underway
• Plain-language block notice instead of a raw carrier error
• Opted-out customers can only be re-enabled by texting START themselves
• Opt-out is per number, not account-wide

Exactly when the disclaimer is added

This is worth being precise about, because "first message only" is the natural assumption and it is not quite what happens.

The line is appended when that customer has never sent you an inbound message, on any of your numbers, for that business. So:

• Cold outbound to a new number gets the disclaimer.
• A second and third cold outbound, if they still have not replied, also get it. It is not once-only, it applies until they engage.
• The moment they reply even once, it stops being added. Every message after that is clean.
• Replies in an existing conversation never get it, because inbound history already exists.

It is also skipped if your message already contains the word "stop" anywhere, so writing your own opt-out wording does not result in it appearing twice.

Opt-out is per number, not account-wide

This catches people out, so it is worth stating directly.

When a customer replies STOP, they are blocked from the specific number they replied to. If your business runs several numbers, they can still be texted from the others, because the carrier tracks the block against that one sending number.

That is carrier behaviour, not a TelBuddy choice, and it cuts both ways:

• If a customer opts out of your marketing line, your support line can still reach them, which is usually correct.
• But texting them from another number after they opted out of the first is, at minimum, ignoring a clear signal. Whether it is legal depends on your jurisdiction and the nature of the message; whether it is a good idea rarely does.

The safe reading is that STOP means STOP, regardless of which number it arrived on.

What you see when a message is blocked

Rather than surfacing the carrier's raw error, TelBuddy shows something like:

⚠️ This customer has opted out (replied STOP) and cannot be texted from this number until they text START to opt back in.

Nothing is broken when you see this. The message was not sent, the customer did not receive it, and no further attempt will succeed until they opt back in themselves.

What this does and does not cover

Covered automatically: the STOP keyword and its common variants, the confirmation message the carrier sends back, and the ongoing block. You do not configure any of it and you cannot break it.

Not covered: A2P 10DLC registration. STOP handling is a runtime protection; registration is the separate approval process that determines whether your messages get delivered well in the first place. Having one does not substitute for the other.

Also not covered: consent before the first message. Carriers enforce opt-out, not opt-in. Whether you had permission to send that first cold message is your responsibility, and it is the part regulators actually care about.

Practical guidance

Do not try to work around an opt-out. There is no supported way to, and attempting one from a different number is the kind of thing that gets a Brand flagged.

Do not treat the disclaimer as consent. Appending "Reply STOP to unsubscribe" makes an unwanted message compliant with opt-out rules; it does not make an unsolicited message appropriate.

Expect the occasional accidental STOP. People send it by mistake, or a colleague replies from the wrong phone. There is nothing you can do from your side, so if it matters, ring them and ask them to text START.

Watch for a rising STOP rate. More than the occasional one usually means the messages are landing wrong: too frequent, unexpected, or from a number the customer does not recognise. Carriers watch this too, and a high opt-out rate is one of the signals that affects deliverability.