It seems its been a while since I have installed any type of headset on a Nortel. I tried using the basic headset and the quick release cord that is designed to to plug right into the headset jack. These didn't work well for the customer so I tried a Plantronics headset amplifier, but I could not get them to work. Are there only particular models that work with the T7316E phones?

I've had good luck with the Jabra GN2100 headset, and GN1200 cord. The cord has an 8-position slide switch inline with it that will match the pinout/mic gain to work with pretty much anything. (Nortel M and T series, Nortel/Avaya IP, Cisco IP, Panasonic, NEC, Ascom, Philips, and Plantronics amps.)

https://img8.jabra.com/sites/Jabra/...ments/Datasheet/GN1200_DS_AP_US_1045.pdf

The headset itself is clear and (in my opinion) comfortable, and they aren't horrendously expensive.