Adjust mic filter level on PPC phone?

[Guest Blakey]

This is related to my post here:

http://www.modaco.com/Voice-not-heard-when...in-t247061.html

I have a (sort of) handsfree kit in my car. Basically I plug the phone headphone socket into the handsfree kit which has a built in amp and it amps anything the phone plays to a nice volume to hear in the car. This works great with TomTom which I can now hear over the car stereo.

However when I get a call, the voice of the caller comes over the amp and I think as this is loud, it kicks in the phone's filter system such that it cuts out all outgoing noise so as to avoid feedback loops etc. This has the net effect that the person on the other end of the phone call cannot hear a word I say as the phone has cut off my voice. Hopefully that makes sense to your clever phone people out there.

So, is there a registry setting or some other thing I can do that will allow this to work? Perhaps all I need to do is to drop the volume of the call right down so that there is as little noise as possible going back into the phone, thus stopping the filter cutting in. But that would mean I would struggle to hear the person calling.

Can this situation be resolved with a reg hack or tweak? Or is there another way around it? Or should I be resigned to not being able to have a phone conversation in this set up?

Does anyone else have a similar set up and how do you deal with it?

Many thanks

Blakey