Company is migrating to VOIP. Which statement is true about utilizing a data network for
Voice over IP traffic?

A.
Voice traffic will require some form of QoS mechanisms in most networks.

B.
Because voice traffic volume cannot be calculated, network bandwidth requirements
must be determined from an existing installation.

C.
Adding bandwidth to the data network is the primary solution to provide for the needs
of voice traffic.

D.
Network congestion must be totally eliminated to provide proper voice traffic
performance.

E.
Voice traffic will require some form of QoS implementation only in congested
networks.

Explanation:
For VoIP to be a realistic replacement for standard public switched telephone network
(PSTN) telephony services, customers need to receive the same quality of voice
transmission they receive with basic telephone services—meaning consistently high-quality
voice transmissions. Like other real-time applications, VoIP is extremely bandwidth- and
delay-sensitive. For VoIP transmissions to be intelligible to the receiver, voice packets
should not be dropped, excessively delayed, or suffer varying delay (otherwise known as
jitter).
VoIP can guarantee high-quality voice transmission only if the voice packets, for both the
signaling and audio channel, are given priority over other kinds of network traffic. For VoIP to
be deployed so that users receive an acceptable level of voice quality, VoIP traffic must be
guaranteed certain compensating bandwidth, latency, and jitter requirements. QoS ensures
that VoIP voice packets receive the preferential treatment they require. In general, QoS
provides better (and more predictable) network service by providing the following features:
• Supporting dedicated bandwidth
• Improving loss characteristics
• Avoiding and managing network congestion
• Shaping network traffic
• Setting traffic priorities across the network

http://www.cisco.com/en/US/docs/ios/solutions_docs/qos_solutions/QoSVoIP/QoSVoIP.html