I have a need to share a line across 8 phones with the single button cBarge feature. Any of these phones should be able to barge into the call with the single button feature. As additional phones barge in, they should join the conference already in progress.
The problem that I am having is as follows. The first phone that barges into the call creates the conference with a single button press. Additional phones that barge get the remote in use message, and have to select the cBarge softkey. This seems like a bug to me, as all phones have the single button cBarge feature enabled. I have tried barging into the call on different phones and in a different order, but the single butoon feature only works for the first phone to create the conference. Additional phones always have to use the softkey to complete the barge and be added to the conference.
CUCM version is 7.1.3. The device pool for these phones is set up to use a SCCP hardware conference on an ISR router. All phones that share the line have been set up with privacy=off, and single button barge=cBarge. In addition, all of the phones have been set with max calls = 8. I see the hardware conference in use with "show SCCP all", so I know that the MRGL is working properly.
The only problem seems to be that after 3 phones are on the conference, aditional phones always need 2 button presses to complete the barge.