Software Conference Bridge in Remote Sites

Unanswered Question
Apr 9th, 2010


I have my main site (HQ) and some remote sites (BR), I have assigned the Conference Bridge (Hardware) in each Media resource group per Site, but in some sites I dont have enough DSP resources for the Conference bridge (the E1 is taking up that dsp) so i was wondering if i could use a Software Conference Bridge for those Remote Sites, I checked and it seems that CCM allows you to have only one software conference bridge (CFB_2). My questions are:

1.- Is it possible to add more Software conference bridge to CCM?

2.- If not is there a workaround for this?

If in the CFB_2 I assign the device pool and location of my remote site and I add this into its Media Resource Group then I can make those conferences in my remote sites but...  the other sites wont have resources to make their conferences too.

I'm trying to do this with Call Manager 7, my Voice Gateways in the remote sites are 2800 series router with a 16-channel (G.711) Voice/Fax PVDMII DSP SIMM PVDM daughter card

Thanks in advance!!

I have this problem too.
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gogasca Fri, 04/09/2010 - 09:37

CUCM SW CFB is a service running in each CUCM server if you want to add "another" SW CFB you need to add another server

You dont really need to add 1 CFB per site, tou need to analyze the traffic and from there determine the number of sessions you need per site

A disadvantage for SW CFB is it only supports G711 so you will be using more BW across the WAN

I would recommend you to analyze traffic flows and get more DSPs for each site if needed

You can check our SRND for MEdia Resources for more details about this planning

allan.thomas Fri, 04/09/2010 - 10:39


As already mentioned, consideration has to be given to the fact that CallManager SF CFBs only support G.711, therefore unless you are using G.711 end-to-end or site-to-site then ordinarily this is not a limitation unless bandwidth is at a premium.  However, if you are using G.729 across the WAN then further complications arise, as you will the have the necessity for transcoding resources and additional DSPs will required.

Unfortunately even if your partial E1 was limited to the absolute minimum of 8 timeslots there still would not be sufficient DSPs for even one hardware CFB based on the PVDM2-16 and therefore your hands are pretty much tied.  I would recommend that you localise your DSPs for CFBs for each remote site or location which will require an additional PVDM2 depending on the number of sessions and participants required.  The 2801, 2811 have two PVDM slots, whereas the 2821 and 51 have three.

The only alternative depends upon the bandwidth between locations if you are seriously consider running G.711.  Remember that this will also impact any QoS Policy that maybe in place on the WAN, particularly if you are paying your carrier to provide QoS.



Hope this helps, pls rate helpful posts.

mezcalito Sun, 04/11/2010 - 03:19

Thanks for your responses!

I know my client needs more dsps, I already told him but he is not sure when he will be able to purchase them. In the meantime I'd like to configure Software Conference Bridge in some remote sites, bandwidth is not a problem the WAN is within the city.

All my Phones are in the partition PT_Internal and each site has its own Device Pool, Location, CSS,  MRG and MRGL, what I've seen is that the conference only works when the Software Conference Bridge has assigned the Device Pool and Location of a remote site, if there is only one Software Conference Bridge in CCM7 how can I share this one to multiple sites? Is this possible? Maybe I'm doing something wrong... don't know

Thanks in advance!

Aaron Harrison Sun, 04/11/2010 - 04:13


For your MRGs and MRGLs, a simple way to arrange this is:

1) Build an MRG for each location (containing media resources) for each type of resource. E.g.







2) For each site, build an MRGL containing the resources you want to use at that site:

HO (Contains HO_CFBs, HO_MTPs, HO_MOHs)

RemoteOffice1 (Contains RemoteOffice1_CFBs,RemoteOffice1_XCODEs, as this site has some local resources)

RemoteOffice2 (Contains HO_CFBs, HO_MTPs, HO_MOHs, as this site has no local resources)

3) Assign the HO MRGL to the HO site, RemoteOffice1 to that remote office, etc...

If you haven't configured MRGs/MRGLs, things are assigned randomly from a default pool (think of it as similar to using the partition). Until you add them to MRGs, I believe that resources are only available to the CCM they register to. This would explain why they currently only work when they are in the same device pool as the remote site phones.



Please rate helpful posts...

allan.thomas Sun, 04/11/2010 - 04:43


Although you have configured a seperate MRG and MRGL for each location, there is one important consideration and that is the region as this dictates which codec is negotiated during the capabilities exchange.

Each device-pool should be configured with a specific region, therefore you need to ensure that the device-pool for your remote office IP Phones are using G.711 within its own region, and similarly G.711 to the Head Office region for where the SW CFBs are registered.



Hope this helps, pls rate helpful posts.


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