Which statement describes the distributed call control model in VoIP networks？（）

• A、The gateway voice-capable device is configured to support call control directly performing call setup， call maintenance， and call teardown
• B、The gateway voice-capable device has a local call routing table configured through a routing protocol.
• C、The gateway voice-capable device relies on a call agent to support call control.
• D、The gateway voice-capable device relies on a gatekeeper to support call setup， call maintenance， and call teardown.