Phone Number Does Not Have Correct Messaging Service Capabilities
ERROR: 21715
PROGRAMMABLE SMS
ERROR
Description
In order for a phone number to work in a Messaging Service it must have at least SMS or MMS capabilities. If it does not have either, it will fail.
Possible Causes
The phone number you are trying to add to the Messaging Service does not have SMS or MMS capabilities.
Possible Solutions
The Active Numbers page in the Twilio Console will display the capabilities of each of the phone numbers in your account.
Find a new phone number that has SMS and/or MMS capabilities depending on your use case and business needs, and add that phone number to your Messaging Service.