Call Barging works on some but not other handsets

I have a strange issue with the call barge feature.

Our customer service team use it in order to train and perform continuous development on the service agents.

Many of the phones we have are identical (polycom IP335) but exhibit different charactaristics with this feature.
With the phones that are working as expected, this is the behaviour that we see:
If a manager wishes to call barge to a phone he will dial *9xxx (xxx = ext no) and the target phone will be dialled into ready for when the agent takes a call. This is the desired behaviour as we don’t want the agent to know they are being assessed nor the manager to have to spend the whole day looking at the queue to see when the agent gets a call.

This brings me to the issue when the feature doesn’t work as expected.
On dialling *9xxx to call barge when an agent is not on a call the call is dropped immediately. This is frustrating the managers as they then need to monitor the queue in order to dial in when the agent is taking the call only.

Can somebody help with what this may be. Phone F/W versions
Boot on a phone that works, on one that doesn’t (I would think this is unimportant though)
Updater on both
SIP on both
Mem1 on both

edit: Should have added PABX firmware ver. 5.1.6 (141001)



Call barge is designed to barge/spy a running call, rather than a handset. This issue sounds like a support ticket that should be raised (via your re-seller if you are an end user) through our support department.


We have actually discovered since that the call barge will connect consistently if the phones have the messages key enabled in place of the second line.
It appears the second line is causing the call barge to drop. I’m not sure myself why this would make a difference but I now have some very happy team leaders and managers as the ‘feature’ works over all phones now.