For those boffins in the know, can you tell me if the telephone control is in the radio faceplate or in the bluetooth module?

I'd like to replace my standard GS radio with the HSE radio. I have been able to get hold of the LR accessory which adds bluetooth to the standard GS radio but only gives voice control. This kit includes the bluetooth module, gateway, wiring and steering wheel controls.

I've also got an HSE radio and faceplate but am interested in how to make this work with the telephone facilities.