This is the hack I thought of to let me use a cheap Wal*Mart wired
> phone with a headset. Simply wire a connection between the coiled
> handset cord and my headset. There are 4 connectors on the coiled
> handset cord, one for talking, one for listening, and a ground each.
> My headset has a 1/8" male stereo jack at the end. The part furtherst
> from the tip would take both the ground wires, and then I just have to
> find which is the mike, and which is the earpiece.
On a standard 2.1 mm headset jack the tip is the mike and the ring is the ear piece. A standard 4 pin modular handset cord uses the two inner conductions for the ear piece and the outer conductors for the microphone.
I have done this on several telephones with varying success. The two big 'ifs' are as follows:
1) The telephone must expect an electret condenser mike, and yes they are polarity sensitive. If the phone is looking for a carbon mike element or an assembly emulating one, you're out of luck. 2) The design of the phone must be such that the mike the ear piece share a common ground. You have 4 wires and 3 pins, so if you can't common the grounds, its not going to happen. You could modify the headset to use a 4 pin connector, but that defeats the purpose of being able to use the headset as is.This all assumes that you are talking about a dial-in-base telephone.
If you have the dial-in-handset type, the base is often nothing more than a weighted cradle that passes tip and ring through to the handset, and none of this applies.
- Ron
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