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Voice quality network requirements
Packet loss may be more tolerable for one codec over another.
Even small amounts of packet loss can greatly affect a TTY/TDD device's (for
hearing-impaired people) ability to work properly.
Packet loss for signaling traffic increases network traffic substantially when loss is greater
than 3%.
Network packet loss
Like delay, Avaya offers customers a tiered approach of packet loss recommendations to
balance new network costs and limitations with business directives. Tools such as Avaya's VoIP
Monitoring Manager (VMM), the Agilent (HP) Internet Advisor, Finisar's Surveyor Explorer,
Radcom's Prism, NAI's Sniffer, and others measure packet loss. Remember that too much
delay or packet mis-order can be perceived as lost packets. It may appear that the network is
losing packets when in fact they have been discarded intentionally because of late arrival at the
endpoint. IP networks are characterized by unintentional packet loss in the network as well as
by discarded packets in the jitter buffers of the receiving endpoints.
The maximum loss of IP packets (or frames) between endpoints should be:
1% or less for best quality depending on many factors.
3% or less for Business Communications quality. Again, this quality is much better than
cell-phone quality.
More than 3% may be acceptable for voice but may negatively impact signaling.
208 Avaya Application Solutions IP Telephony Deployment Guide
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