Retro fit a push button switch to the telephone control unit and radio to mute the call and allow you to answer the call.Or retro fit multi function steering wheel from another b7 a4 but you will loose the SPORT button function.The choice is yours and anything possible if you have the money and time and knowledge.Or a good forum ha ha

Just thought,you could swap the switch for the multifunction display on the steering wheel and fit the telephone button there and retro fit multifunction wiper switch and code for the dash enable so the hole lot could be done with some effort.