When I plug in a wired headset and make a Headset Button on the phone the volume is so low it's unusable. I have to take off the headset button and just manually lift the handset and program an Answer and Release button. I can't seem to make it work like the old TD line. Put it in Headset mode and then the SPKR button becomes the hookswitch. What am I doing wrong? Or is it just this way now because of the 3.5mm headset jack on the side of the phones now?

Yes, you will have to get a adaptor lead for the plantronics box to connect the unit in to the 3.5mm jack to work

Thank you.