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Chapter 9 Catalyst DSP Provisioning

Understanding the Catalyst DSP Resources

9-2

Cisco IP Telephony Network Design Guide

78-11103-03

Understanding the Catalyst DSP Resources

The DSP resources on the new Catalyst 4000 and 6000 gateway modules

essentially provide hardware support for IP telephony features offered by

Cisco CallManager. These features are hardware-enabled voice conferencing,

hardware-based MTP support for supplementary services, and transcoding

services.

Catalyst-enabled conferencing is the ability to support voice conferences in

hardware. DSPs are used to convert voice over IP (VoIP) sessions into

time-division multiplexing (TDM) streams, which can then be mixed into a

multiparty conference call.

The Catalyst MTP service can act either like the original software MTP resource

or as a transcoding MTP resource. An MTP service is the ability to provide

supplementary services such as hold, transfer, and conferencing when using

gateways and clients that do not support the H.323v2 feature of

OpenLogicalChannel and CloseLogicalChannel with the EmptyCapabilitiesSet.

MTP is available as a software feature that can run on Cisco CallManager or a

separate Windows NT server. When MTP is running in software on

Cisco CallManager, 24 MTP sessions are supported. When MTP is running on a

separate Windows NT server, up to 48 MTP sessions are supported. The new

Catalyst gateway modules can support this same functionality, but they provide

the service in hardware.

Transcoding is in effect an IP-to-IP voice gateway service. A transcoding node

can convert a G.711 voice stream into a low-bit-rate (LBR) compressed voice

stream, such as G.729a. This is critical for enabling applications such as

integrated voice response (IVR), voice messaging, and conference calls over

low-speed IP WANs. MTP transcoding is currently supported only on the Catalyst

voice gateways.

Table 9-1 shows DSP resources that can be configured on the Catalyst voice

services modules.

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Cisco WS-X4604-GWY - VoIP Gateway Especificaciones Pagina 188