I'm running CUCM 11.5 and firmware 12.0 on a set of Cisco 8851 phones. Barge works great, and cBarge works great. However, no matter what I do, I can't get single button barge to work. Any ideas would be great.
Could you check this,
To enable single button barge for all users, set the single button barge/cBarge Policy to barge. If this parameter is set to Off, configure single button barge for each phone by setting the Single
Button Barge field in Phone Configuration
Also I found a bug affecting 8851 while using 12.0 firmware for barge feature
All of that had already been configured. There is nothing to configure on the phone configuration page except the Built-in bridge, which is globally enabled in the Service Parameters. We aren’t trying to barge while ringing so that bug wouldn’t seem to apply.
It seems like Single Button Barge Feature is not supported on 8851 Phone.
You can cross check that in CUCM unified reporting page. [ as below ]
Unified reporting --> Unified CM Phone feature List -->Generate new report --> Select phone as 8851 and Feature as Single button barge . You wont see that mentioned in the List features table. But if you select some other model phone , say, 7965 or 7941 , you would see that feature in the list.
Hope that helps.