Voice quality network requirements
212 Avaya Application Solutions IP Telephony Deployment Guide
Because it does not use compression, G.711 offers the highest level of voice quality.
Unfortunately, there is a trade-off with higher bandwidth usage. In situations where bandwidth is
scarce, such as across WAN links, G.729 offers a good compromise with lower bandwidth
usage, but still good fidelity audio.
Compression codecs use twice as many DSP (digital signal processor) resources than the
G.711 codec. Each call using a compression codec uses two DSP resources - one for sampling
and one for the compression. On the TN2302AP (MedPro) circuit pack (and on the G700 VoIP
engine) there are 64 DSP resources. Thus, the number of calls supported by one MedPro or
G700 is:
●
64 G.711 calls
●
32 compressed calls (for example, G.729)
●
Some number in-between for a call mix.
The formula for calculating the number of calls one MedPro supports is
Generally, G.711 is used within LANs because bandwidth is abundant and inexpensive whereas
G.729 is used across WAN links because of the bandwidth savings and adequate voice quality.
Table 41: Comparison of speech coding standards
(without IP / UDP / RTP overhead)
Standard
Coding Type
Bit Rate
(kbps)
MOS-LQO
1
,
2
1. As predicted. Measured according to ITU-IT Recommendation P.862
(PESQ). See draft Recommendation P.862.2, application guide for PESQ.
2. Given MOS-LQO values for American English.
G.711
PCM
64
4.37
G.729
CS-ACELP
8
3.94
G.723.1
ACELPMP-MLQ
6.3
5.3
3.78
3.68
Number of uncompressed calls
(
)
2
Number of compressed calls
(
)
×
64
≤
+
Summary of Contents for Application Solutions
Page 1: ...Avaya Application Solutions IP Telephony Deployment Guide 555 245 600 Issue 3 4 1 June 2005 ...
Page 20: ...About This Book 20 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 21: ...Issue 3 4 1 June 2005 21 Section 1 Avaya Application Solutions product guide ...
Page 22: ...22 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 106: ...Call processing 106 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 124: ...Avaya LAN switching products 124 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 139: ...Issue 3 4 1 June 2005 139 Section 2 Deploying IP Telephony ...
Page 140: ...140 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 186: ...Traffic engineering 186 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 204: ...Security 204 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 228: ...Avaya Integrated Management 228 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 274: ...Reliability and Recovery 274 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 275: ...Issue 3 4 1 June 2005 275 Section 3 Getting the IP network ready for telephony ...
Page 276: ...276 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 356: ...Network recovery 356 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 366: ...Network assessment offer 366 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 367: ...Issue 3 4 1 June 2005 367 Appendixes ...
Page 368: ...Appendixes 368 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 394: ...Access list 394 Avaya Application Solutions IP Telephony Deployment Guide ...
Page 414: ...DHCP TFTP 414 Avaya Application Solutions IP Telephony Deployment Guide ...