Originating caller-id / DID. Maps to Twilio's from.
OptionalStatusOptional status-callback URL for lifecycle events. Maps to Twilio's statusCallback.
Destination number (E.164). Maps to Twilio's to.
The TwiML executed when the call connects (our <Connect><Stream>). Maps to Twilio's twiml.
The REST payload ITwilioRestLike.calls.create accepts (the subset we use).