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Calls Dropping CUCM -


Hi There,

Looking for some advice or perhaps even just a starting point with an issue we are having with our calls. 

We are finding that when customers are calling into our service and staff place the calls on hold to transfer a call when they complete the transfer there is no audio at either end. 

From some testing I have done a pattern I have noticed that when the staff member you are transferring the call to answers and you transfer the call within 1-5 seconds the majority of these work fine. However if the call is left on hold for 10/20/30 seconds or so and you transfer the call this is when the audio fails. The call still stays connected it doesn't disconnect or anything however there's no audio at either end.

The majority of our users are on Cisco Jabber and some sites are using Cisco 7841s and we can replicate the issue on both physical and softphones. The majority of our calls are coming into Hunt Groups. 

The initial reports of this started when we migrated to SIP I am just wondering if anyone has experienced similar problems? 

2 Replies 2

VIP Advisor VIP Advisor
VIP Advisor

In the service parameter for callmanger service: Whats the value for "Duplex Streaming Enabled"? If it is on default "False" set it to "True".
I have seen some SIP Trunk installations, where this helps for such audio issues.
Since, then I always set it to "True" in every installation.

Scott Leport
Rising star
Rising star

Hi there,

If it occurred when migrating to SIP, I am assuming that you're talking about calls to / from the PSTN which are affected and not on-net calls between IP phones registered to the same CUCM?

You may also need the command "midcall-signaling passthru" or "midcall-signaling passthru media-change" applied globally on your SBC (I have assumed Cisco CUBE) as I've seen that resolve a couple of weird audio issues with hold / transfer scenarios. Or even just resolve audio issues after 15 mins (when the UPDATE message gets exchanged between CUBE and SIP provider).

Midcall signaling passthru documentation and how to configure it / apply it:


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