You received an inbound phone call to a Twilio phone number owned by your trial account, but the 'From' number is not a Verified Caller ID on your account. In order to receive calls to a Twilio number during a free trial, you must first verify your ownership of the phone number that is placing the call.
The ‘From' number of the inbound call is not a Verified Caller ID. Trial accounts can only receive inbound calls from verified phone numbers.
You can verify phone numbers from the phone numbers section of your account portal.