Avaya Voicemail Pro CD 4.2 700459357 Manuel D’Utilisation

Product Description
IP Office 4.2

© 2009 AVAYA All rights reserved.

Page 135

Issue 18.s.- (22 May 2009)

Quality of Service (QoS) is a measure of the performance of a network that reflects the availability of network
service and the quality of network transmissions. The term itself refers to a number of networking technologies
and techniques and does not necessarily restrict itself to any single protocol or standard.

There are a number of measures that can be taken on the LAN and WAN to make them 'good enough' to carry
voice traffic. Some of these are the implementation of standards based QoS protocols while are simply a
matter of network architecture and good network management practices.  

The term 'good enough' is intentional. Every customer will have different expectations and different budgets to
work to. Some will be willing to upgrade their networks to use the best possible equipment and practices. To
others the additional expense may be viewed as unnecessary.

Examples of standards based Quality of Service protocols include DiffServ and 802.1p/q.

 

VCM's are required to support the following scenarios:

· Usage of Embedded Voicemail on the Small Office Edition (used as a memory boost by compressing the

voice files).

· Internal phone calls between an IP device and a non-IP device.

· Analog/digital phones to IP trunks (SIP/H.323) including managed Frame Relay and managed IP VPN

(provides echo cancellation).

· IP phones to ISDN or PSTN trunks (convert IP to TDM and vice-versa).

IP device to IP device
Call progress tones (for example dial tone, secondary dial tone, etc) do not require voice compression
channels with the following exceptions:

· Short code confirmation, ARS camp on and account code entry tones require a voice compression

channel. 

· Devices using G.723 require a voice compression channel for all tones except call waiting. 

When a call is connected: 

· If the IP devices use the same audio codec no voice compression channel is used. 

· If the devices use differing audio codecs, a voice compression channel is required for each. 

“Direct Media” is a VoIP concept that circumvents resources (TDM bus, Gateway) within the system and
improves the voice quality. If two IP devices are connected on the same system, a direct LAN connection
between them will be established once the call has been set up (as long as they use the same Codecs).

It is possible for an IP device to be physically located at one site while being registered at a different site. In
this case, even for VoIP across the WAN the VCM would not be used, as long as the two IP devices involved in
a phone call are registered on the same system.

A Data Channel is only required for Remote Access (RAS), Internet Access, and Voicemail connections:

· 10 PCs accessing the Internet over a single line = 1 Data Channel. If multiple lines are used (Multi-Link

PPP) then as many data channels are required (e.g. 128k i.e. 2B channels requires 2 data channels)

· 10 users dialing in from home on 10 separate lines onto the LAN = 10 Data Channels

· Voicemail is an IP application on the LAN (i.e. one data channel is required for each voicemail port used)

 

Note:  IP end-points do NOT require data channels