CUCM MOH on multisite

Unanswered Question
May 4th, 2010

Hi All,

we have sub and pub in two different sites. Bandwidth in sub site is much higher than pub site. I like MOH to play only from sub site for all remote sites and only play from pub site if call being on hold locally on pub site. I haven't created MRG and MRGL, so we have default MRG. I define two server groups, one with sub first and one with pub first. then create two device pools with those groups. if I assign device pool with sub first to all phones in all remote sites, and assign device pool with pub first only on pub site, is it going to fulfill this requirement?

any suggestion would be very appreciated.


I have this problem too.
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Aaron Harrison Tue, 05/04/2010 - 12:01


Within an MRG, the devices will be load balanced.

Within an MRGL, they will be used in the order specified.

So create an MOH MRG for sub site and pub site, and order those within two MRGLs (one sub first, one the other way round). Then assign to dev pools as you described.



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alex goshtaei Tue, 05/04/2010 - 13:38

thanks for the reply,

yes, that works well except there is one issue. I want to play multicast MOH rather than unicast. when I check both server to play multicast, MOH is not playing on either phones. I think because I can't use the same multicast IP address on both servers.

any suggestion would be appreciated.


allan.thomas Tue, 05/04/2010 - 13:58


Firstly you should configure different base IP Addresses for each MoH server and configure to increment on port or on ip address.  However, you need to be aware of the fact that either the port or base ip address is incremented for each codec, for example say your base address is, this would infact be the base address for G.711ulaw, then for G.711alaw and so on.

So ensure that if you use increment on ip address that you take this into consideration when you specify the base address on the other MoH server.  The same is applicable if you increment on port number.

However, there maybe a number of factors why your Multicast is not working, but lets start with the basics.  Have you enable multicast for the MRG, there is a checkbox that specifies that the MRG is used for MoH.  When you placed calling-party on-hold do you hear silence or tone-on-hold?



Hope this helps.

Aaron Harrison Tue, 05/04/2010 - 14:01


For multicasting to work you need a lot of stuff:

1) Within CCM, enable the MOH sources for multicasting

2) Within CCM, enable the MOH servers for multicasting - you would (as you suggest) set a different base IP address for each server (I'd normally change the third octet by one to ensure you have a large enough IP space for both servers, as you need to increment the IP address per audio source/codec)

3) Enable mcast on your MRGs

At this point if you go on hold and get silence, it normally means that your CCMs should be multicasting and your phones are listening... so you need to:

4) Increase the 'max hops' for each MoH source (default is 2 hops, which is too few for most topologies)

5) Enable your LAN/WAN for multicasting (often not done)



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alex goshtaei Tue, 05/04/2010 - 14:51

I did the same procedure, but still it's silence. there is no beep, only silence. It means MOH is available but not playing. both phones are connected to the same switch.

Aaron Harrison Tue, 05/04/2010 - 15:11


It more likely means MoH is playing, but not available to the endpoints due to a problem with your mcasting config.

MoH doesn't go from phone to phone, it goes from CCM to phone...

Are you saying it is working for one phone, or neither?


Aaron Harrison Tue, 05/04/2010 - 23:15


Silence means you haven't been through the checklist I put up earlier.

You are either not sending the multicast traffic properly (likely the hop count) or your LAN/WAN is not configured for multicast routing. Unless you use a lot of MoH you would probably be best advised to leave it on unicast, unless you are confident with the multicast LAN/WAN configuration.

Can't help more unless you provide more information about what you have on configured on your network and it's topology.



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