We implemented the work-around mentioned at the following link to fix the Delayed call transfer problem and that is now fixed, but since then we have created two new problems:
The two new problems after making the changes to fix the delayed transfer problem are:
Internal IP Phone to IP Phone no problem, but external PSTN phone to IP phone intermittently results in one way audio. This is generally noticed when external PSTN phone calls an internal IP phone, but may happen also when an internal IP phone calls an external PSTN phone.
When an external PSTN phone and an IP phone are in a conversation and if the call is transferred to another IP phone the call will altogether drop.