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Avaya Application Solutions platforms
72 Avaya Application Solutions IP Telephony Deployment Guide
 
Voice over IP (VoIP)
The IG550 features a VoIP engine that provides voice services over IP data networks. The 
IG550 allows you to use many types of telephones and trunks that do not directly support VoIP. 
The media gateway translates voice and signalling data between VoIP and the system used by 
the telephones and trunks, as follows: Avaya TIMs convert the voice path of traditional circuits 
such as analog trunk, and T1/E1 to a TDM bus inside the media gateway. The VoIP engine then 
converts the voice path from the TDM bus to a compressed or uncompressed and packetized 
VoIP on an Ethernet connection.
The G250 provides VoIP services over the LAN and WAN. The G250 supports the G.711, 
G.729A, G.729AB, and the G.726A codecs, for up to 80 concurrent calls. 
Configuring media gateway options
The media gateway provides the following configuration options to help you ensure continuous 
telephone services:
You can configure the media gateway to use up to four servers. If the MGC is an 
S8700-series server, the first server on the list will normally be the primary C-LAN board 
connected to the server. If the MGC is an S8400 or S8500, the first server on the list will be 
either the primary C-LAN board connected to the server or an Ethernet port on the server 
that has been enabled for processor Ethernet connections. If the MGC is an S8300, the 
first server on the list will be the IP address of the S8300. The remaining servers will be 
alternate C-LAN boards connected to the server (S8400, S8500, or S8700-series 
Servers), an S8300 configured as an Local Survivable Processor (LSP), or the port 
enabled as the Ethernet processor port on an S8500 configured as an LSP. In addition, the 
gateway can also register to the Standard Local Survivability engine (see the SLS 
description that follows).
Using the connection preserving migration feature, you can configure the media gateway 
to preserve the bearer paths of stable calls in the event that the media gateway migrates to 
another MGC (including an LSP), including migration back from an LSP to the primary 
MGC. A call for which the talk path between parties in the call has been established is 
considered stable. A call consisting of a user listening to announcements or music is not 
considered stable and is not preserved. Any change of state in the call prevents the call 
from being preserved. For example, putting a call on hold during MGC migration will cause 
the call to be dropped. Special features, such as conference and transfer, are not available 
on preserved calls. Connection preserving migration preserves all types of bearer 
connects except BRI. PRI trunk connections are preserved.
You can configure Standard Local Survivability (SLS) to enable a local media gateway to 
provide a degree of MGC functionality when no link is available to an external MGC. SLS 
is configured on a system-wide basis using the Provisioning and Installation Manager 
(PIM). Alternatively, SLS can be configured from the individual media gateway itself using 
the CLI. SLS supports all analog interfaces, ISDN BRI/PRI trunk interfaces, non-ISDN 
digital DS1 trunk interfaces, IP phone, and IP Softphone.