Opt-Out Keyword Handling for Toll-Free SMS
Opt-Out Keyword Handling for Toll-Free SMS
Section titled “Opt-Out Keyword Handling for Toll-Free SMS”Toll-free SMS numbers have a carrier-enforced opt-out layer that operates outside of SIPSTACK. This layer cannot be removed or customized. Understanding how it works is important for managing your messaging program and avoiding unexpected behavior.
How Opt-Out Works on Toll-Free SMS
Section titled “How Opt-Out Works on Toll-Free SMS”When a recipient texts STOP to your toll-free number, the carrier’s network automatically opts them out and sends this reply on behalf of the network:
NETWORK MSG: You replied with the word “stop” which blocks all texts sent from this number. Text back “unstop” to receive messages again.
No further messages can be sent to that recipient from your toll-free number until they opt back in.
How Opt-In (Re-subscription) Works
Section titled “How Opt-In (Re-subscription) Works”When a recipient texts START or UNSTOP, the carrier’s network opts them back in and sends:
NETWORK MSG: You have replied “unstop” and will begin receiving messages again from this number.
Key Points
Section titled “Key Points”| Behavior | Detail |
|---|---|
| STOP handling | Enforced at the carrier network level — cannot be disabled or customized by SIPSTACK |
| Opt-back-in keywords | START or UNSTOP |
| Applies per toll-free number | Each toll-free number maintains its own opt-out list |
| Webhook notification | SIPSTACK still passes the STOP/START keyword message to your webhook |
Difference From Long Code Opt-Out
Section titled “Difference From Long Code Opt-Out”Long code (10-digit) numbers use SIPSTACK’s built-in opt-out handling, which you can read about in SIPSTACK Support for Opt-Out Keywords. Toll-free numbers have an additional carrier-enforced layer on top of this.