NETW 250 Final Exam

NETW 250 Final Exam

1. (TCO 1) ITU recommendation G. 711 is also referred to as _____ (Points : 5)






Question 2.2. (TCO 1) What’s a typical amount of downtime associated with PSTN business services? (Points : 5)






Question 3.3. (TCO 2) Which circuit-switched Private Branch Exchange (PBX) hardware allows internal phones and extensions to be connected to the PBX? (Points : 5)






Question 4.4. (TCO 2) An end user of a(n) _____ uses line keys on the phone panel to select and access telephone company lines. (Points : 5)






Question 5.5. (TCO 5) Which transport layer protocol is not used by voice packets in VoIP? (Points : 5)






Question 6.6. (TCO 5) In the RTP header, _____ is used by the receiver to detect lost packets and to ensure that received packets are played back in proper order? (Points : 5)






Question 7.7. (TCO 4) Which of the following audio codecs, in its original form, requires 64 Kbps of bandwidth? (Points : 5)






Question 8.8. (TCO 4) Which of the following audio codecs, in its original form, requires the least amount of bandwidth? (Points : 5)






Question 9.9. (TCO 5) Which of the following techniques help reduce VoIP bandwidth consumption? (Points : 5)






Question 10.10. (TCO 3) Which of the following VoIP equipment is typically seen in a residential environment? (Points : 5)






Question 11.11. (TCO 6) Which SIP method/response is typically generated to signal the end of a call session or dialog? (Points : 5)






Question 12.12. (TCO 6) Which SIP method/request or response is shown below?INVITE SIP/2.0

Via: SIP/2.0/UDP;branch=z9hG4bK887chdhds

Max-Forwards: 70

To: John <>

From: Mary <>;tag=1982301747


CSeq: 413159 INVITE

Contact: <>

Content-Type: application/sdp

Content-Length: 142 (Points : 5)






Question 13.13. (TCO 6) In H.323 call signaling, _____ is used for terminals to exchange capabilities and preferences such as audio and video codecs during a call setup. (Points : 5)






Question 14.14. (TCO 6) Which of the following is not a typical function of VoIP gateways? (Points : 5)






Question 15.15. (TCO 7) Which of the following facts about Local Number Portability (LNP) is not correct? (Points : 5)






Question 16.16. (TCO 7) Which of the following is a telephony feature that was made possible by VoIP? (Points : 5)






Question 17.17. (TCO 8) What’s the name of the gateway interface/port that connects an analog phone? (Points : 5)






Question 18.18. (TCO 8) Which of the following is typically required to connect SIP trunks to legacy PBXs and analog phones? (Points : 5)






Question 19.19. (TCO 9) 200 seconds of total holding time during the Busy Hour generates a traffic load of _____ (Points : 5)






Question 20.20. (TCO 9) Given that the targeted call blocking probability remains the same, which of the following PBX systems will support the least amount of traffic during the Busy Hour? (Points : 5)






Question 21.21. (TCO 12) Sending an INVITE message to every phone number on a network in search of vulnerable devices based on received responses is referred to as _____ (Points : 5)






Question 22.22. (TCO 12) Even if the voice traffic is encrypted, an intruder may capture and interpret _____ to discover who calls whom, when calls involve specific phones, and other information.(Points : 5)






Question 23.23. (TCO 11) Network connectivity is a(n) _____ a good user experience on VoIP services. (Points : 5)






Question 24.24. (TCO 11) Which of the following is not correct about echo in a voice call? (Points : 5)






Question 25.25. (TCO 10) IEEE 802.1p defines eight priority classes for _____ prioritization. (Points : 5)






Question 26.26. (TCO 13) Which of the following could be an indicator of high-end desktop IP phones? (Points : 5)






Question 27.27. (TCO 13) Having a third-party assume all PBX management responsibilities is referred to as a(n) _____ solution. (Points : 5)






Question 28.28. (TCO 13) What does this formula calculate?(the expected returns from a project – the cost of implementing a project) / the amount of time required to complete the project. (Points : 5)





Question 2.

Question 3.

Question 4.

Question 5.

ABC Inc. is planning to lease a 512 Kbps frame relay connection between two PBXs from two branch locations. The audio codec used on the trunk is G.729A with a 20-millisecond packet duration. Assume the targeted call blocking probability for ABC Inc. is 1% (i.e., 0.01). How much traffic volume/load (in Erlangs) can this trunk support?

120 call attempts, with an average call duration of 10 minutes during the Busy Hour have been observed on the connection. What’s the current traffic volume/load (in Erlangs) on this trunk connection? Compare the current traffic volume/load to the supported traffic volume/load calculated above. Does the frame relay trunk have enough capacity to support the current traffic volume/load? (Points : 10)

Question 6.

Suggest, in one paragraph, two methods that could help ABC Inc. reduce the end-to-end delay of its cross-country VoIP services. (Points : 10)