I am trying to interface a handsfree headset to a desktop speaker phone. I am trying to use the speakerphone speaker and microphone leads to connect to the handsfree set so I can leave the phone's handset in the cradle. The microphone in the phone base has only two wires to it. I connected these to the handsfree mic leads but it doesn't pick up the sound. Is this just a impedance mismatch or are the two mics (phone and handsfree) just not the same type? How do I tell what type they are and/or test them? Any suggestions on how I can make this work?