Phone System · 1 min read
Error 21211: Invalid "To" Phone Number
What this error means
Error 21211 means the number in the To field could not be recognized as a valid phone number, so the call or message was never sent.
Destination numbers should use E.164 format: a plus sign, the country code, and the full subscriber number with no spaces or punctuation.
``
+[country code][area code][subscriber number] +15551234567 ``Common causes
- The number is not in E.164 format, or the country code is missing or wrong.
- The number has a typo or is missing digits.
- The same number is used as both sender and recipient.
- The message is being sent to a short code or an alphanumeric sender ID.
- The number has an unsupported prefix.
- A form, import, workflow, or contact record stored malformed phone data.
How to fix it
- Open the contact and review the phone number on the record.
- Add the correct country code and remove spaces, dashes, brackets, and letters.
- Confirm the From and To numbers are different.
- Re-send the message or place the call again.
- If the number came from a form or import, fix the source so new contacts are saved correctly.
Prevent it from happening again
- Use a phone field with country selection on your forms.
- Clean up phone columns before importing contacts.
- In workflows, add a condition that checks the phone field is not empty before sending SMS.