Abstract: An aftermarket hands free unit for mobile wireless telephone use in a vehicle. The hands free unit commands the telephone to enter either an active hands free mode, AHF, or alternatively, a privacy hands free mode, PHF, in response to a user-operated switch on the unit. In one embodiment, these commands are generated by a microprocessor in the unit that sends an ID inquiry to the phone that enables the unit to identify and be used with different model phones. This microprocessor also repeats AHF and PHF commands to the telephone to maintain the desired mode. The hands free speaker in the unit is uniquely clam shelled between the housing and a circuit board, and mode switching is effected by a clever optical switch mounted in a finger recess in the unit housing. Duplexing is fixed by the unit to appropriately marry the capabilities of the phone.