21664: 'FallbackFrom' cannot be used with a 'From' sender

You can't use FallbackFrom when From is set to a specific phone number or RCS Sender. To use FallbackFrom, send the message with MessagingServiceSid so Twilio can select the RCS Sender from the Messaging Service's Sender Pool.

• You sent both FallbackFrom and From in the same request, and From contains an E.164 phone number such as +15105550100.
• You sent both FallbackFrom and From in the same request, and From contains an RCS Sender such as rcs:sender_id.
• You used FallbackFrom without routing the message through a Messaging Service. FallbackFrom only works with MessagingServiceSid.

• If you want native RCS fallback, remove From and send the message with MessagingServiceSid plus FallbackFrom.
• If you want to send without RCS fallback, remove FallbackFrom and use From only. For direct RCS sending without fallback, set From to the RCS Sender ID and set To to the recipient's rcs: address.
• If you need a specific fallback sender, provide it in FallbackFrom and make sure it belongs to the same Account SID. The fallback sender must be a Twilio phone number in E.164 format, an alphanumeric sender ID, or a short code.
• If you are passing a Messaging Service SID in From, move that value to MessagingServiceSid. This is the recommended way to combine Messaging Service sender selection with FallbackFrom.

• Messages resource
• Messaging Services
• Send and receive RCS messages