Creates a call event subscription. A webhook_id is required so that we know to which url the events shall be sent. Call states can be used to limit the states for which call events are sent. A target_type and target_id may optionally be provided to scope the events only to the calls to/from that target.
To include the recording url in call events, your API key needs to have the "recordings_export" OAuth scope. Added on April 23rd, 2021 for API v2.