單項選擇題Which statement is true about a distributed call control environment and the processing of dialed digits from an IP phone？（）

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.


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1.多項選擇題What are two major sources of delay that can be managed by QoS in voice-enabled networks？（）

A.propagation delay
B.voice packet serialization delay
C.congested egress queues
D.header overhead
E.packets dropped because of CRC errors

2.多項選擇題Which two statements are true about voice ports on a router？（）

A.Calls to the PSTN can be made via the use of FXO or T1/E1 trunk ports.
B.Calls to the PSTN can be made via FXS or T1/E1 trunk ports.
C.Analog and IP phones can be connected to the VoIP network via FXO or T1/E1 trunk ports.
D.Calls between analog phones that are attached to the FXS ports in a VoIP network can be completely processed by voice-enabled routers.

3.單項選擇題Which statement is true about Foreign Exchange Station （FXS） ports on a router？（）

A.The FXS interface allows an analog connection to be directed at the public switched telephone network （PSTN’s） central office.
B.The FXS interface connects directly to a standard telephone，fax machine，or similar device and supplies ring，voltage，and dial tone.
C.The FXS interface connects directly to an IP phone and supplies ring，voltage，and dial tone.
D.The FXS interface connects directly to ISDN voice channels.

4.多項選擇題Which two statements are true about the digital audio in a VoIP network？（）

A.Standard encoding techniques create an uncompressed digital data rate of 4000 bps.
B.Standard encoding techniques create an uncompressed digital data rate of 8000 bps.
C.Standard encoding techniques create an uncompressed digital data rate of 64，000 bps.
D.Voice quality is not a concern if compression is not used.
E.Two methods of quantization are linear and logarithmic.
F.Two methods of compression are u-law and a-law.

5.多項選擇題Which two statements are true about analog to digital conversion of voice signals for use in digital telephony networks？（）

A.The three required steps in the analog to digital conversion are sampling，encoding，and compression.
B.The three required steps in the analog to digital conversion are sampling，quantization，and compression.
C.The three required steps in the analog to digital conversion are sampling，quantization，and encoding.
D.The output of the sampling process is a pulse code modulation （PCM） signal.
E.The output of the sampling process is a pulse amplitude modulation （PAM） signal.