Thanks both,
619Tech, unfortunately pressing the hold key still does not allow the user to diasable the headset. Display reads phone needs to be idle. Am using the 'red' button for putting the call on hold, which I presume is the correct way to do it.
Tech Electronics, I appreciate the scenario is a little odd. The users spends a LOT of time of the phone so requested a headset. However, there are occasions when he has conferences around his desk with team members and likes the loudspeaker option. The group listen is a useful feature, but I don't think a viable solution in this scenario. Will have to teach him how to disable the headset shortcut on his phone when he wants to use loudspeaker.
The last option I have is upgrading his phone to 5340 and bolting on the headset option so fully integrated with the phone. We have others in the office using this model handset so would be worth testing with them.