Error 21211

ERROR - 21211

Invalid 'To' Phone Number

You attempted to initiate an outbound phone call, but the Called phone number you supplied was not a valid phone number or was incorrectly formatted. Twilio accepts phone numbers in E164 format: [+] [country code] [subscriber number including area code].

This error will also occur if you attempt to place a call or send a message from a Twilio phone number to itself (i.e. putting the same Twilio number in the To and From parameters).

Possible Causes

• The formatting of the 'To' number you supplied was invalid.
• You attempted to send a message or place a call from a Twilio number to itself.

Possible Solutions

• Ensure you have formatted your phone numbers in E164 format: [+] [country code] [subscriber number including area code]
• Ensure you have used the correct country calling code for the phone number you are calling.
• Ensure you are not attempting to call or message from a Twilio number to itself.