21666: 'FallbackFrom' requires MessagingServiceSid

When you use FallbackFrom, also provide MessagingServiceSid. FallbackFrom sets the SMS or MMS sender Twilio uses if an RCS message can't be delivered over RCS. This parameter works only with a Messaging Service.

• Your request included FallbackFrom but didn't include MessagingServiceSid.
• Your request used FallbackFrom with From instead of sending through a Messaging Service.
• Your application attempted to set an RCS fallback sender without routing the message through a Messaging Service.

• Add MessagingServiceSid to the request when you use FallbackFrom.
• Send the message through a Messaging Service that you use for RCS messaging.
• If you don't need RCS fallback, remove FallbackFrom and send with From or MessagingServiceSid alone.
• Verify that the fallback sender you specify in FallbackFrom is an SMS- or MMS-capable sender that belongs to the same Account SID.

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