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20 Cards in this Set

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True or False: A single VoIP channel requires less bandwidth than a single PSTN voice channel.

True

What ITU-standard waveform codec does the PSTN use?

G.711

What ITU-standard codec is preferred for use on links that regularly experience high network traffic?

G.729

How do DPCM and ADCPM conserve bandwidth?

They issue only the bits that represent a differential between an actual signal and a predicted signal, and rely on the receiving node to reconstruct the signal based on a predicted value plus the differential

What is one disadvantage to using vocoders to encode speech?

The signals they construct at the receiving end can sound fake.

What function does the H.225 protocol provide, as part of the H.323 VoIP specification?

Handles call setup, call routing, and call termination.

What is one advantage to using SIP over H.323?

SIP uses fewer processing and port resources.

How do media gateway controllers help to improve the performance of media gateways?

They offload call signaling and routing functions from the media gateways, allowing the gateways to focus on data transmission.

True or False: The RSVP Quality of Service approach emulates a circuit-switched network connection?

True

What does RTP add to packets that compensates for UDP's lack of reliability?

Sequence numbers

On a VoIP network that uses the DiffServ QoS technique, which of the following makes certain that a router forwards packets within a given time period?

Expedited Forwarding

What protocol manages addressing for multicast groups?

IGMP

Which of the following protocols would be used by a video bridge to invite a video phone to join a video conference?

H.225

Suppose your organization's PSTN and VoIP systems are integrated, and that your VoIP system adheres to architecture specified in H.323. What performs translation between the PSTN's signaling protocols and H.323 on your network?

H.323 gateway

You are using Skype to initiate a video call with a friend in another state. Which of the following protocols is generating segments at the Transport layer of this transmission?

UDP

What device enables multiple media gateways to communicate?

MGC

How does RSVP help improve QoS?

It establishes a path between the sender and receiver that is guaranteed to supply sufficient bandwidth for the transmission.

The Traffic Class field in an IPv6 datagram serves the same function as which of the fields in an IPv4 datagram?

DiffServ

In wireless communication, to exchange information, two antennas must be tuned to the same ______.

Frequency

In wireless systems, the transmitting antenna focuses its energy directly toward the receiving antenna which results in a point-to-point link.

Fixed