I have a 6620 and just purchased a Nokia HF-3 potable car kit. The Nokia site said the 6620 was not supported, but I bought it anyway. Anyway, I plugged the car kit into my phone, and the 6620 first said "Charging", and then told me that the enhancement was not supported. Why??? Does anyone know if there are patches, drivers, etc. that Nokia puts out (or anyone puts out) to make Nokia phones work with Nokia enhancements? I think it would be fairly easy. Any thoughts?
It says it isn't supported, because it isn't; whatever special this car kit needs is not in the phone (and that's why the phone was not listed as supported for the car kit, obviously).
There may be so called updated firmware releases available for your phone (from your nearest authorized Nokia service center), but it is unlikely to add support for a car kit that was not originally supported.
There are no user-installable drivers or such to make it happen either, I'm afraid.
I'd try to sell (or give) the unsupported car kit to someone with a phone it supports & buy one supported for the 6620 instead: