Error 63015
Product: Programmable SMS
ERROR - 63015
Channel Sandbox can only send messages to phone numbers that have joined the Sandbox
Channel Sandbox can only send messages to phone numbers that have joined the Sandbox
Possible Causes
This message failed to be delivered to the user because it was sent from a Sandbox to a phone number that has not joined your Sandbox
Possible Solutions
Instruct the recipient to join your Sandbox by sending the join phrase or keyword shown on the Sandbox page in your Twilio Console.