Chapter 17: Voice Over IP Key
1. Internet telephony is also called IP telephony.
2. VoIP is sometimes called Internet telephony.
3. VoIP relies primarily on circuit switching.
4. A VoIP call must remain solely on the Internet or other TCP/IP network.
5. The VoIP approach converts a digital signal format into an analog voice waveform for transmission over the
Internet.
6. While VoIP sounds like a single network protocol, it actually includes a variety of distinct protocols that
work in combination to handle the necessary functions.
7. Signaling protocols associated with a specific vendor’s IP PBX might be proprietary.
8. Skype uses proprietary protocols.
9. A SIP Uniform Resource Identifier (URI) looks like an e-mail address.
10. H.323 is actually a series of many protocols.
11. A VoIP “soft phone” requires a broadband Internet connection.
12. VoIP “soft phone” software usually encrypts the voice signal prior to transmission.
13. All Internet telephony options provide emergency 911 services.
14. Internet voice calling can involve plugging a USB-compatible telephone into the USB port of a computer.
15. Analog devices such as fax machines cannot be plugged into an ATA
16. An IP phonecan connect directly to an IP network without an adapter.
17. Traditional phones have more features than IP phones.
18. Some IP phones are wireless.
19. Wi-Fi phones provide better mobility than cell phones.
20. Some Wi-Fi phones are able to switch from Wi-Fi access to a cell phone network when they move out of
range of the Wi-Fi network.
21. Residential VoIP services do not work with existing phone jacks.
22. Spam does not occur over Internet telephony.
23. Every communication system has a built-in delay, though often imperceptible to users.
24. Synchronous means, literally, “without time”.
25. The Internet’s technical infrastructure was not originally designed for real-time voice communications.
26. Packet loss does not occur over the Internet.
27. Latencyis a problem that affects VoIP’s quality of service and that VoIP providers have to design around.
28. Cordless phones work during power outages.
29. A network that is up and running 99.999% of the time is available all but 5 minutes and 15 seconds of a
year.
30. The difference between a network availability of 99% and 99.999% is inconsequential.
31. Greater security is an advantage of VoIP over traditional phone service.
32. Traditional phone service has been available for more than a century.
33. One important technical difference between Internet telephony and the traditional telephone system is that
Internet telephony transmits voice information using:
34. The VoIP protocols that assess user availability, ring the destination device, establish a call, and terminate a
call session are called:
35. SIP is an example of a:
36. H.323 is an example of a:
37. The VoIP protocols that handle the transmission of the voice call between endpoints are called:
38. Which of the following is a VoIP transport protocol?
39. Using an information exchange similar to HTTP, SIP operates at what layer of the OSI reference model?
40. What institution develops specifications for SIP?
41. What institution develops specifications for RTP?
42. What institution develops specifications for H.323?
43. What device can connect directly to an IP network without an adapter because it internally converts the
telephone audio signal into digital format for transmission over the IP network?
44. An IP phone that can connect over a Wi-Fi link is called a:
45. Which of the following currently provides the greatest user mobility?
46. A term describing communications such as text messaging that do not require the use of a central timing
source is:
47. A term that describes introducing a slight delay to even out the timing of received packets is which of the
following?
48. Usually in voice communications, the small but noticeable lost of parts of a conversation are called:
49. Degradation in call quality that results from timing problems, such as variations in packet arrival time is
called:
50. Within the context of computer networking, a term that relates to the time delay between the transmission
and reception of packets over a network is called:
51. An unauthorized person masquerading as a legitimate VoIP caller is called:
52. The phenomenon of packets being dropped on a network that is overwhelmed with traffic or as part of a
signal that is degraded during transmission is called:
53. Communications that are continuous in time, such as a voice conversation, are called:
54. The usual technical approach to overcoming jitter is to:
55. The decades-old metric for phone service reliability is a percentage of time that the network should be
available which is?
56. 99% availability means that a network is expected to be down for a total of how much time per year?
57. 90% availability means that a network is expected to be down for a total of how much time per year?
58. 99.999% availability means that a network is expected to be down for a total of how much time per year?
59. VoIP is short for ______________________________.
60. VoIP is a set of standards designed for transmitting ____________________ over the Internet or other IP
network.
61. IP PBX is short for _____________________________________________.
62. Some protocols associated with VoIP are open standards developed by standards organizations such as the
_____________________________________________ and the
63. In the context of VoIP, a voice ____________________ is simply a voice conversation or other exchange of
information between users.
64. A caller who wants to establish a voice session uses the called party’s SIP identity, the
_____________________________________________ to issue a SIP INVITE request.
65. The H.323 family of protocols also includes encoding standards, which transform analog signals into a
standard ____________________ format.
66. One simple (and free) approach to Internet telephony is to install VoIP software on a computer and use it
with a headset to make a voice call. This type of implementation is often called a ____________________.
67. A VoIP soft phone requires a headset (or microphone and speakers), a sound card, VoIP software, and a
____________________.
68. ATA stands for ____________________.
69. An ______________________________ is a device that serves as an analog-to– digital converter (ADC)
between an analog phone and an Ethernet network connection to an IP network.
70. Many residential users of voice over the Internet subscribe to a commercial VoIP service from their local
cable provider or ____________________.
71. Residential VoIP services require a high-speed Internet connection, such as a cable access link via a cable
modem or high-speed ____________________ link.
72. In addition to voice mail and call waiting, some of the features of VoIP phone services include VIP ringing,
caller ID, caller ID blocking, and ____________________.
73. ____________________ buffering refers to buffering that introduces a delay in real time based on
prevailing network conditions.
74. ____________________ buffering refers to buffering that introduces a fixed time delay to even out the
timing of packets.
75. Spam over Internet telephony refers to the problem of unwanted solicitations over VoIP systems;
abbreviated as ____________________.
76. UPS is short for ______________________________.
77. A UPS is used as an alternative power source during ____________________.
78. One primary benefit of VoIP is ____________________.
79. Packet loss occurs for a variety of reasons including if a network segment becomes overwhelmed with
traffic or if a signal is ____________________ during transmission.
80. Power outages are not a problem for phones directly connected to the PSTN because power is supplied by
the _______________________.
81. Describe some of the functional components of VoIP protocols:
82. Describe some of the functions performed by SIP.
83. Describe a SIP information exchange:
84. Why are voice and video more time sensitive than data?
85. What is meant by the word “convergence”?
86. Describe a trade-off between security, privacy, and law enforcement requirements in VoIP
implementations.
87. Describe some multimedia features of an IP phone:
88. Explain why Wi-Fi phones currently have some limitations relative to cell phones.
89. What are the trade-offs businesses must weigh when considering a VoIP implementation?
90. Generally, what are some VoIP alternatives business can choose?
91. Explain why the unified communications provided by a VoIP infrastructure is a benefit for businesses.
92. Explain why the unified communications provided by a VoIP infrastructure is a benefit for individuals.
93. Retransmitting lost voice packets is not always effective. Explain why.
94. Explain why power outages are a challenge for VoIP implementations.
95. In what way can privacy be an issue for VoIP networks?
96. What institutions in the United States have traditionally overseen local voice services?
97. Describe the taxation questions that arise for VoIP services.