(TCO 1) The two variants of the ITU G.711 codec are _____ (Points : 5)

Question 2.2. (TCO 1) What’s the typical uptime percentage associated with PSTN business services? (Points : 5)

Question 3.3. (TCO 2) Which circuit-switched Private Branch Exchange (PBX) hardware connects a PBX to Central Office (CO) switches? (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 better suited for carrying real-time voice traffic in VoIP? (Points : 5)

Question 6.6. (TCO 5) In the RTP header, _____ is a random value and increments by 1 for each packet sent. (Points : 5)

Question 7.7. (TCO 4) Which of the following audio codecs, in its original form, requires 8 Kbps of bandwidth? (Points : 5)

Question 8.8. (TCO 4) Which of the following audio codecs, in its original form, is best known for preserving sound quality? (Points : 5)

Question 9.9. (TCO 5) Which of the following techniques could potentially fail to reduce VoIP bandwidth consumption? (Points : 5)

Question 10.10. (TCO 3) Which of the following has motivated the adaptation of VoIP technologies, especially in business environments? (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) Refer to the following SIP INVITE method/request. Who is the caller?

INVITE s..n@abc.com SIP/2.0
Via: SIP/2.0/UDP pc14.chicago.com;
Max-Forwards: 70
To: John &..n@abc.com>
From: Mary &..y@chicago.com>;
Call-ID: a..0@pc14.chicago.com
CSeq: 413159 INVITE
Contact: &..y@pc14.chicago.com>
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) A VoIP gateway translates _____ (Points : 5)

Question 15.15. (TCO 7) Which of the following is an ITU standard that defines international public phone numbers? (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 to the Central Office (CO) switch or PBX? (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 traffic load remains the same, which of the following call blocking probabilities will demand the least amount of trunk resources (e. g., trunk circuits)? (Points : 5)

Question 21.21. (TCO 12) _____ attacks involve large numbers of spoofed calls that overwhelm the access bandwidth or trunk capacity of a phone system. (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 troubleshooting echo? (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 is not an indicator of high-end desktop IP phones? (Points : 5)

Question 27.27. (TCO 13) A _____ VoIP solution typically has only phones remaining on the enterprise LAN. (Points : 5)

Question 28.28. (TCO 13) Choose the correct formula for calculating Return on Investment (ROI). (Points : 5)

1. (TCO 5) ABC Inc. replaced its legacy circuit-switched PBX with an SIP-based VoIP system on its Ethernet LAN. When capturing and observing voice packets using Wireshark, which header contains the sequence number and time stamp information needed for playing back the audio at the receiving end? Describe, in one paragraph, how the sequence number and time stamp are used to for this purpose. (Points : 10)

Question 2.2. (TCO 5) What’s the primary factor that determines the required bandwidth per VoIP conversation? List and explain, in one paragraph, two methods that could help reduce the bandwidth consumption of a VoIP call on WAN links. (Points : 10)

Question 3.3. (TCO 6) What’s the H.323 terminology for an SIP server (or VoIP server)? Describe, in one paragraph, two tasks for which an IP phone needs to communicate with an SIP server. (Points : 10)

Question 4.4. (TCO 10) When processing an Ethernet voice frame, where in the frame does an 802.1p-enabled switch look for the priority marking? When processing an IP voice packet, where in the packet does a QoS-enabled router look for the priority marking? Describe, in one paragraph, two circumstances under which prioritizing voice traffic has little effect on its QoS guarantee. (Points : 10)

Question 5.5. (TCO 9) Use the Erlangs and VoIP Bandwidth Calculator at http://www.erlang.com/calculator/eipb/ to complete the following question.

The IP PBX of ABC Inc. observed 120 call attempts during the Busy Hour of the WAN connection to its service provider. The average call duration was 10 minutes. What’s the traffic volume/load in Erlangs of the WAN connection?

The audio codec used on the WAN connection is G.711 with a 20-millisecond packet duration. Assume the targeted call blocking probability for ABC Inc. is 1% (i.e., 0.01). How much bandwidth (in Kbps) is required to carry the previously calculated voice traffic volume/load? (Points : 10)

Question 6.6. (TCO 11) Describe, in four paragraphs, the International Telecommunication Union’s rule for various tiers of voice transmission end-to-end latency (i.e., 150 milliseconds, 200 milliseconds, above 250 milliseconds, and above 500 milliseconds). (Points : 10)