Codecs
Issue 3.4.1 June 2005
211
and cross-talk effects. In principle, the transmit loss of telephones could be made very large
followed by signal amplification in the receiving telephone. In practice however, the transmit loss
should be limited to prevent the electrical voice signal from dropping below electrical
background noise. This has resulted in the adoption of transmit loss and receive loss values
around 8 dB and 2 dB, respectively, although country-specific values may actually deviate quite
significantly from these values.
The loss plan administration provided by Avaya Communication Manager software is primarily
intended to control signal losses in telephones and gateways, and not to control echo. However,
in case of severe echo, the administered loss can be changed to a different plan. In principle, an
increase of the loss between two endpoints by a certain amount will increase the echo loss by
twice this amount. In general, it is not advised to use loss plan administration in this way without
consultation with Avaya Services personnel. It is better to reduce the echo by strategic
deployment of echo cancelers.
Tone Levels
The level of call progress and DTMF tones played out through telephones must also adhere to
specified levels in order to be satisfying for the average user. Again, respective standards are
country specific and can be set under administrative control. The volume of received call
progress tones can be adjusted by the telephone volume control.
Codecs
Codecs (Coder-Decoders) convert between analog voice signals and digital signals. Avaya
supports several different codecs offering varying bandwidth usage and voice quality, including:
●
A G.711 codec produces audio uncompressed at 64 kbps
●
A G.729 codec produces audio compressed at 8 kbps
●
A G.723.1 codec produces audio compressed at 5.3 kbkps or 6.3 kbps
Table 41: Comparison of speech coding standards (without IP / UDP / RTP overhead)
on
page 212 provides comparisons of several voice quality considerations associated with some of
the codecs supported by Avaya products.
Note:
Note:
Toll-quality voice must achieve a MOS (Mean Opinion Score) of 4 or above. The
MOS scoring is a long-standing, subjective method of measuring voice quality.
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 ...