Jabber sometimes performs Transfer instead of Merge

[jasonCutcher]

Jabber Version - 14.1.3.57304
CUCM Version - 12.5.1.14900-63

Users are reporting, very infrequently, that Jabber will perform a cold transfer on two parties instead of a full conference when pressing the "Merge" button.  

The exact procedure that has two outcomes is as follows.  
Call 1 is placed on hold.  
Call 2 is initiated from the same DN. 
"..." is pressed, followed by Merge > Call 1

Usually this results in a full conference of all three parties.  Infrequently it results in Call 1 and Call 2 being conferenced, but the User is removed from the call.  

I've verified the correct behavior by watching recordings of screen captures.  Users are hitting buttons correctly.  

Has anyone seen this behavior and knows the cause and/or fix?

Thanks in advance.

[Carlo Poggiarelli]

Hi Jason, 

Does it happen for both internal and external call?

Can you please attach an SDL trace here indicating all numbers of all called users?

Thanks

Regards

Carlo

[jasonCutcher]

I have not seen this duplicated internally, and my attempts to personally recreate the issue have failed so far.  
Unfortunately, I cannot share SDL logs or anything that would contain phone numbers.  I was hoping there would be a general "oh, change this setting" sort of answer, based on the symptoms. 

[Carlo Poggiarelli]

So You are saying that this behaviour is random. If this happens with external users from inside, I suspect a codec mismatch between called users and CUCM Conference bridge.  Are you able to add a transcoding resource to see if it can fix the issue?

Please let us know

Regards

Carlo