Triple-Play Service Deployment

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Since the 64 Kbps bandwidth requirements for G.711 exceed the
capabilities of most POTS modems, G.723.1 is emerging as a low
bandwidth standard. G.723.1, a combination of G.721 and G.723,
operates at 6.3 Kbps and 5.3 Kbps respectively.The voice quality of
G.723.1 is similar to PCM.
Codec Type Voice Samples per Frame Voice Samples per Frame
(Default) (Maximum)
PCMU/PCMA 2 10
G.723 1 32
G.726-32 2 20
G.729 2 64
G.728 4 64
Table 8.1 Voice samples per frame for VoIP codecs
VoIP Service Quality
Chapter 8: Troubleshooting VoIP
Objective measures for a subjective experience
Packet networks were designed originally for bursty, non-real-time
applications such as file transfers and email. This type of traffic
tolerates delays and usually has built-in retransmit capabilities in
the event of data loss or corruption. Retransmission enables errorfree
performance at the application level. However, VoIP service
delivery places more stringent requirements on these networks
that were structured to support data payloads. As a result, new
class of service (CoS) mechanisms must be enabled in the packet
network to achieve acceptable levels of performance to support
toll quality VoIP.