Upcoming changes to withheld caller ID behavior for <Dial> calls

Twilio is changing how we persist caller ID information for <Dial> calls where the inbound caller ID is withheld; e.g. ANONYMOUS, RESTRICTED, etc. Today Programmable Voice translates the alpha string into digits. This behavior will change and we will begin to persist the alpha string from the inbound call to the outbound <Dial> leg for calls where the caller ID is withheld by the calling party.

This represents a significant change in the behavior of our APIs and developers will need to ensure that their systems can gracefully handle alpha characters in the To and From fields for requests and responses to the /Calls API, in TwiML,webhooks, and in status callbacks.

If the callerId parameter is used with the <Dial> verb, the outbound caller ID will reflect what was provided with callerId, regardless of the caller ID on the inbound call.