21665: Invalid 'FallbackFrom' sender

The FallbackFrom parameter must be a valid SMS or MMS sender. Aceptable values include an E.164 phone number, an alphanumeric sender ID, or a short code that exist in your Twilio account.

• FallbackFrom contains a phone number not in E.164 format (e.g., 15105550100 instead of +15105550100).
• FallbackFrom contains a phone number in an unsupported format (e.g., with spaces or parentheses).
• FallbackFrom contains a phone number that is not owned by the Twilio Account
• FallbackFrom contains an RCS Sender format (e.g., rcs:sender_id).

• Use a valid SMS/MMS sender format: an E.164 phone number (e.g., +15105550100), alphanumeric sender ID, or short code.
• Do not use an RCS Sender format in FallbackFrom. The RCS Sender for the message is selected automatically from the Messaging Service sender pool.
• Ensure the Twilio account being used owns the phone number.