Has anyone ever use a throat mic similar to what security guards use during concerts for use with cell phone in convertible?

I was told this is the solution to be able to use your cell phone while the top is down without having to hold the cell to your ear (illigal here).

Here is what I am talking about: EBay Throat Mic FBI Style

I would like to know who has ever tried these things and if it would work in a convertible environment.

It is very difficult to use a cell phone in a convertible and I hate having to close the roof for a phone call.