I am looking for information on the pinout for the DuraFon 1X headset 2.5mm jack. We have a base unit and handset deployed in a very loud environment and I've been asked to look for noise cancelling and noise attenuating headsets with microphones to plug into the handset. I see in the manual that the handset has a 2.5mm jack for use with the EP PTT Headset. This headset unfortunately doesn't do any noise cancelling and only covers one ear. I would like to try alternate headsets, but need information on the pinout.