twilio-whatsapp-send-message

Use client.messages.create with from and to numbers prefixed with whatsapp:+E.164 and a body parameter. For messages outside the 24-hour window, pass contentSid and contentVariables referencing an approved template instead of body.

The 24-hour window allows free-form messages only within 24 hours of the user's last inbound message. Outside that window you must send an approved template message, otherwise the free-form message fails silently.

Join the sandbox by texting join <your-code> to +14155238886, then send messages from the sandbox sender. Sandbox participants must re-join every 3 days, and trial accounts are limited to 50 messages per day.

Common causes include sending free-form outside the 24-hour window, an invalid destination number (error 63003), exceeding the 80 messages-per-second rate limit (63018), or the business not accepting Twilio's Meta invitation (63020).

Yes, media attachments up to 16 MB are supported in free-form mode by passing mediaUrl with a publicly accessible URL. Template messages do not support ad-hoc mediaUrl attachments in the same way.

The default limit is 80 messages per second per sender, which can be raised to 400 MPS for text-only traffic on request. Undelivered queued messages fail after 4 hours, and the sandbox throttles to 1 message per 3 seconds.