Hello,
I'm sharing with you a small presentation of a modification I've just made to an ASI radio, I have incorporated Bluetooth without altering the car radio, keeping all the original functions with no external module.
In short, as if the car radio had been Bluetooth since 1982
In other words, when you're in radio mode, the electrical antenna is extended, and when you switch to Bluetooth mode, it retracts, which avoids having the antenna extended unnecessarily all the time you're using the car radio in BT mode.
It's also possible to add an external microphone to provide a hands-free kit through the car radio.