Product: Elastic SIP Trunking
You attempted to initiate an outbound phone call, but the From number you specified is not a verified Outgoing Caller ID for your account. In order to use a phone number as the Caller ID on outgoing calls, you must first validate your ownership of that phone number.
From number used to make outbound call not a Twilio number or not a verified caller ID
Change the callerID used in the From field of the SIP INVITE to a Twilio number on your account or verify your number by visiting the Console Verified Caller IDs or REST API.