課程名稱︰ 網際網路電話系統
課程性質︰ 選修
課程教師︰ 逄愛君
開課學院： 電機資訊學院
開課系所︰ 資訊所
考試日期（年月日）︰ 2007/11/13
考試時限（分鐘）： 180分鐘
是否需發放獎勵金： 是
（如未明確表示，則不予發放）
試題 :
IP Telephony (Midterm Exam)
1. (20%) Voice Quality:
(a) Pleade describe and compare the evaluation for voice quality. (10%)
(b) Are these evaluation tools adequate for VoIP? Why or Why not? (5%)
(c) Please elaborate on the challenge of voice/speech quality for VoIP
in terms og delay, jitter, and packet loss. (5%)
2. (15%) Bandwidth Requriment of VoIP:
(a) How does a VoIP system provide low-bandwidth voice transmission? (10%)
(b) Is it applicable to PSTN? Why or Why not? (5%)
3. (20%) RTP and RTCP:
(a) How to calculate RTT and jitter. (5%)
(b) What is the timestamp in RTT packets? (5%)
(c) What is the difference between sequence number and timestamp? (5%)
(d) What is the difference between SSRC(Synchronization Source) and CSRC
(Contributing Source)? How are they applied to mixer and translator?
(5%)
4. (20%) Design the "Follow Me" service in the H.323 system (assume that the
user is registered at different GKs). Please include
(a) The message flow for Registration Procedure.
(b) The message flow for Call Delivery Procedure.
5. (25%) H.323:
(a) Why is GateKeeper optional in H.323? (5%)
(b) Please describe and compare two man types of multipoint conference in
H.323 (10%)
(c) What is the purpose of "Master-Slave Determination" in H.245? (5%)
(d) Please give an example of call flow where inter-gatekeeper
communication is needed but their communicating protocol was not
specified by H.323. (5%)
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