My car phone can receive door bell rings (via iphone) but I cannot speak due to the need to press the mic icon on the phone screen to communicate.

Its illegal to use or touch your phone in the UK, but using the built in car phone is ok. Ive missed a few deliveries etc when driving as i cannot speak to the caller.

Is there anyway to speak direct from the car phone to a doorbell caller without having to enable the phone mic.?