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IP Telephony Features

The IP Office gatekeeper allows the registration of up to 190 IP extensions on the IP406, 360 IP extensions on the IP412 and 384 IP extensions on the IP500, less the number of analog and digital TDM telephones already configured on the system.
The Voice Compression Module provides the H.323 gateway function that allows IP extensions to make calls to other non-IP devices. The maximum number of simultaneous calls is limited by the number of channels available on the Voice Compression Module. IP Office must be fitted with an optional Voice Compression Module to enable IP telephony.
Silence Suppression
Silence suppression is a technique used to make the best use of available bandwidth, such as the connection over which the caller is listening, not speaking. Silence suppression works by sending descriptions of the background noise, rather than the actual noise itself, during gaps in conversation thereby reducing the number and frequency of voice packets sent on the network. Background noise is very important during a telephone call. Without noise the call will feel very unnatural and give a perception of poor quality.
IP Office supports a wide range of voice compression standards including G.711, G.729a and G.723.1. The method of compression can be either automatically established on a call-by-call basis or be configured on an individual extension basis.
Fast Start
When fast start is supported by an IP extension, this facility reduces the protocol overhead allowing an audio path to be established more quickly.
Out of Band DTMF
When out of Band DTMF is configured on an IP extension, the extension will signal to the other end of the connection which digits need to be regenerated by a local DTMF generator on behalf of the sending IP extension. This is useful when navigating external voicemail systems and Auto-Attendants.
Direct Media Path
Direct Media Path allows the speech path between two IP extensions (after call setup) to be routed directly to each other. This allows the IP Office system to free up voice compression resources after establishing the end to end connection, allowing the resources to be used in the most efficient way.
Auto-Create Extensions
IP Office can automatically create an extension entry for new IP phones added onto the local area network. In cases where the local area network is not secure this facility can be disabled, but simplifies installation of IP telephone systems
Fax Transport (Avaya Proprietary)
Fax Transport allows fax calls to be routed over VoIP trunks between IP Office systems on an IP network using a proprietary IP Office transport protocol.
Fax Transport T.38
IP Office supports the standardized protocol "T.38" for transporting FAX calls between IP Office and SIP trunks or SIP endpoints. T.38 is only supported on IP Office 500 hardware. It requires the IP Office to be equipped with VCM 32 or VCM 64 modules.

T.38 allows the reliable transmission of Fax messages over a IP channel independent of Codec used for the Voice communication.

Platforms Supported:

IP500 only, must be fitted with VCM32 or VCM64 module.

Trunk Types Supported:


Extensions Supported:


T.38 Transport Layers Supported:

UDPTL (with optional redundancy error correction).

T.38 Versions Supported:


Call Types Supported:

Voice calls which transition to fax relay on detection of fax tones.

Calls which are negotiated as fax only

LAN Switch Support

Avaya recommend the use of Extreme switches for IP telephony applications. For more information, contact Extreme Networks.

© 2010 AVAYA
15-601041 Issue 20.f.-
18:14, 25 February 2010

Performance figures, data and operation quoted in this document are typical and must be specifically confirmed in writing by Avaya before they become applicable to any particular order or contract. The company reserves the right to make alterations or amendments at its own discretion. The publication of information in this document does not imply freedom from patent or any other protective rights of Avaya or others.

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Last Modified: 09/07/2009