Error 21712

Product: Programmable SMS

Error - 21712

Phone Number or Short Code is associated with another Messaging Service.

A Twilio phone number or short code can only be associated with one Messaging Service at a time.

Please delete the number from its existing Messaging Service before attempting to add it to a new Messaging Service. See here for a code sample. Removing a Twilio number from a Messaging Service will not remove the number from your account.