Supported Plantronics Headsets with the T38G

[wayson]

Hello,
I have a Yealink SIP-T28P phone. I was sent an email by your tech support showing that a Plantronics SupraPlus HW261N noise cancelling headset with an A10-16 adapter cord would work on this phone. It does not. I was also very clear that I did not want a headset that would require an amplifier. I was assured the above headset would work. The caller cannot hear me, so somehow the microphone on the headset is not transmitting through the phone. I can hear the other caller through the headset. Is there a setting somewhere to fix this. We have tried 4 different headsets with 3 Yealink phones, same model, in my office. Please advise.
Wayson
541-622-2034, this number is where the headset it plugged in. Medford Oregon