I have a Nortel 1140e with a GN Netcom headset that works fine. I need to be able to move that to a Cisco 7962 as we upgrade. During testing we discovered that the GN Netcom did not work on the Cisco. Is there a different cord that we need or can we change the end to a different pin out? Is it possible that we have missed a setting on the Cisco phone to enable the headset port on the back?