[URGENT HELP] Car Bluetooth Microphone doesn't work with Sola

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http://forum.xda-developers.com – I have an Xperia Sola (stock rooted ICS). And I have a Hyundai Verna (2011 Model). It is sold as the name of Hyundai Accent(2011) outside India. The Car has a built in Bluetooth in the stereo system. My Xperia Sola pairs up with the car just fine. I can play music via Bluetooth and Make / Receive Calls through Bluetooth, But the problem is that during calls the phone doesn't use the Car's microphone, because of which the person on the other end cannot hear me properly (as the phone's Mic is being used). I have reformatted my phone, lots of times. Tried it with other Xperia Solas and t (HowTos)