问题:
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.
● 参考解析
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