A.sampling
B.packetization
C.quantization
D.serialization

A.The router that is directly connected to the IP phone will look up the called number in its call routing table.
B.The router that is directly connected to the IP phone will inform its call agent when a service request is detected.
C.When the IP phone is picked up，the IP phone initiates the service request.
D.The directly connected router passes the collected digits to its call agent，and the call agent looks up in its call-routing table the called number.