Sticky Sender makes sure the same From phone number is selected when sending messages via Messaging Services a particular recipient. This allows your application to consistently send messages to your user from a single recognizable phone number.

When Sticky Sender is enabled, Twilio will maintain a mapping of the To and From phone numbers. This mapping is created after the first message is sent from your Messaging Service to a particular recipient. Any future messages sent to that recipient from that Messaging Service will also use the same From number.

Disabling and re-enabling Sticky Sender

If Sticky Sender is turned off, any existing mappings will no longer be referenced, but they will not be instantly deleted. This means that if you toggle Sticky Sender back on in the future, any existing mappings will be referenced again, unless they expired due to age (see below).

Removing a number from the Messaging Service

When a Twilio phone number is removed from your Messaging Service, all Sticky Sender mappings associated to the removed Twilio number are deleted.

If you need to reset the mapping for a particular number without removing the number, please contact Twilio support.

Note: If the number is added or removed from a Messaging Service associated with an A2P 10DLC Campaign, it will trigger the registration (or de-registration) process and the number will be available for use only after that process is complete.

Sticky Sender time-to-live (TTL)

Twilio's data retention policy automatically deletes stale Sticky Sender mappings that have not been used in over a year. Any Sticky Sender mappings that are actively used will be unaffected.

For full details, see Messaging Services - Sticky Sender.