We're having an interesting issue concerning mainly Jabber. When a user starts a conference call, they'll call the first person, and talk with them no problem. They will then call the second person. Second person and the initiator can talk fine here. However, once they merge the calls together, the initiator is not able to be heard. The other two parties can communicate fine.
It seems to happen when it is a mix of desk phone, and Jabber soft phone users, so we've looked into codecs a little, but never found anything that stood out. Any ideas?
What is providing your conference bridge? Is it CUCM or DSPfarm on GW?
Sounds like IP routing to/from the conference bridge issue to me. Who cannot hear whom on the conference? Does it work for IP phones only, how about IP phone and PSTN only, how about Jabber only?
Callers are A B and C
A calls B, then puts B on hold and calls C. A then merges the call.
B and C are able to talk/hear each other fine, but A can only hear, and cannot speak on the call.
CUCM is providing the conference bridge. If a conference is setup using only IP phones, or only Jabber phones, or Jabber and only external parties, there's no problem. It seems to only happen when the initiator is on Jabber, and another party is using an internal IP phone. And....unfortunately it's intermittent...
Seems that the RTP stream is dropped from Jabber to CUCM (which is used as conference bridge using software conferencing) as mentioned by Chris.
Check if this is dropped because of routing or firewall device blocking RTP stream from data vlan to voice-vlan/server-vlan