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
≤
+
Содержание Application Solutions
Страница 1: ...Avaya Application Solutions IP Telephony Deployment Guide 555 245 600 Issue 3 4 1 June 2005 ...
Страница 20: ...About This Book 20 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 21: ...Issue 3 4 1 June 2005 21 Section 1 Avaya Application Solutions product guide ...
Страница 22: ...22 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 74: ...Avaya Application Solutions platforms 74 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 106: ...Call processing 106 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 124: ...Avaya LAN switching products 124 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 139: ...Issue 3 4 1 June 2005 139 Section 2 Deploying IP Telephony ...
Страница 140: ...140 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 186: ...Traffic engineering 186 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 204: ...Security 204 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 214: ...Voice quality network requirements 214 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 228: ...Avaya Integrated Management 228 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 239: ...Reliability Issue 3 4 1 June 2005 239 Figure 69 S8700 Media Server in a high reliability configuration ...
Страница 274: ...Reliability and Recovery 274 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 275: ...Issue 3 4 1 June 2005 275 Section 3 Getting the IP network ready for telephony ...
Страница 276: ...276 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 350: ...Implementing Communication Manager on a data network 350 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 356: ...Network recovery 356 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 366: ...Network assessment offer 366 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 367: ...Issue 3 4 1 June 2005 367 Appendixes ...
Страница 368: ...Appendixes 368 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 394: ...Access list 394 Avaya Application Solutions IP Telephony Deployment Guide ...
Страница 414: ...DHCP TFTP 414 Avaya Application Solutions IP Telephony Deployment Guide ...