adding conference bridge to CUCM 6.1

Unanswered Question
May 30th, 2009


Maybe someone has done this before:

At the moment it's not possible to make conference calls with external (over pstn) useres with CUCM 6.1. I have a 7206VXR Router (H.323 Gateway) with a PA-VXA-1TE1-30+ and a PA-VXC-2T1E1+ card in it. Last one has 30 DSPs on it. I want to add a IOS conference bridge to Callmanager using that DSPs on the 7206VXR router to allow conferencing and transcoding.

Callmanager Version is 6.1

IOS Version is 12.4.25 (IP)

What settings do I have to use on callmanager and what do I have to configure on the router?

Thanks in advance!

I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 4 (1 ratings)
David Schwarzhans Sat, 05/30/2009 - 06:06

part of it, yes. I started with this:

Gateway#configure terminal


Gateway(config)#sccp local FastEthernet 0/0

Gateway(config)#sccp ccm >IP< priority 1

but it is not possible to enter any command starting with "sccp".

Could it be, that I only have to configure the dspfarm part and then the system is intelligent enough that it uses the dsp resources on the gatway for conferencing?

Jaime Valencia Sat, 05/30/2009 - 16:43

Prerequisites for Conferencing and Transcoding for Voice Gateway Routers

DSP Resources

The router must be equipped with one or more of the following network modules or voice DSP modules to provide DSP resources for conferencing, transcoding, and hardware MTP services:










•PVDM2 on Cisco 2800 series or Cisco 3800 series

Cisco CallManager and Cisco IOS Interoperability Guide

Configuring Enhanced Conferencing and Transcoding for Voice Gateway Routers

Table 25-1 Conference Bridge Types



if this helps, please rate

David Schwarzhans Sun, 05/31/2009 - 02:22

Ok, that helps. If I understand it correct, it is not possible to add a IOS conference bridge to Callmanager if not one of the above DSP Modules is installed on the router. Right?

But how can I use the 30 DSPs that are on the PA-VXC-2T1E1+ card? Are they useless? Or is it somehow possible to configure them that conferencing could still be enabled in this voice network with the given hardware?

David Schwarzhans Tue, 06/02/2009 - 00:09

Ok, here is the confirmation from TAC Engineer:


I checked on this and found that the PA can use their DSPs only for voice termination

As per the information I have from 2003

“ The 7200 platform cannot natively use its DSPs for transcoding or conferencing. I have checked

same and indicating that there is nothing currently on the roadmap to support this.

The customer will have to offload the transcoding and conferencing function to another site with C5510-based or NM-HDV C549-based DSPfarms.“


This Discussion