Information Technology Reference
In-Depth Information
Chapter 14
“Do I Know This Already?” Quiz
1.
C. H.323 is the ITU standard that provides a framework for the transport of voice,
video, and data over packet-switched networks.
2.
D. The default codec in Cisco VoIP dial peers is G.729, which has an 8 kbps bit rate.
3.
C. RTP operates at the transport layer of the OSI model.
4.
C. The H.225 standard defines the procedures for call setup and signaling.
5.
B. An Erlang is a unit that describes the number of calls in an hour.
6.
B. VAD reduces traffic by not transmitting packets when there is silence in voice
conversations.
7.
C. cRTP compresses the RTP, UDP, and IP headers.
8.
B. LLQ is recommended for VoIP networks.
9.
A. The local loop is located between the traditional phone and the CO switch.
10.
C. Jitter is the variance in the amount of per-packet delay incurred during the trans-
port of packets across the network, such as packets in an IP telephony voice call.
Q&A
1.
Tr ue. Cis co recommends low-latenc y queuing for VoIP net work s.
2.
False. H.323 is an ITU standard, and SIP is an IETF standard for multimedia.
3.
Tr ue. A n Erlang is a telecommunic at ion s t raffic unit of meas urement repre s ent ing the
continuous use of one voice path for 1 hour.
4.
VA D . Vo i c e - a c t i v i t y d e t e c t i o n s u p p r e s s e s p a c k e t s w h e n t h e r e i s s i l e n c e .
5.
Dejitter buffers are used at the receiving end to smooth out the variable delay of
received packets.
6.
Tr ue. With CC S, a s eparate channel (from the bearer channels) is u s ed for s ig naling.
7.
False. You use FXS ports to connect to phones and FXO ports to connect to the
PSTN.
8.
Tr ue. S S7 implements c all s et up, rout ing, and cont rol, en s ur ing that inter mediate and
far-end switches are available when a call is placed.
9.
Interactive voice response (IVR) system. IVR systems connect incoming calls to an
audio playback system that queues the calls, provides prerecorded announcements,
prompts the caller for key options, provides the caller with information, and transfers
the call to another switch extension or agent.
10.
customer service departments, and other call centers.
