Is something like this doable?
I get a call in my phone. My phone is connected with Arduino via bluetooth. (with Bluetooth shield) Arduino answers the call. And then it transfers the audio to the bluetooth headset I have on me. It should take back the audio i speak and send it to the phone.
I know its will be complex, but something like this is doable?
Would be like 2 devices connected to the Shield at a time.
What kind of phone are you working with? What role does the Arduino have in your project?
My phone is Android,upgradable to the latest version of Android if that matters someway.
Arduino is the ECU in my project and together with many other things that Arduino controls, It needs to notify me when I get a call and then connect it to my headset.
ADD :
I want the rest of the process to stop while having a call. (Rest of the functions arent related with phone though). So I think the only way to do that is what I proposed?
Am I clear enough? No replies makes me feel that I am not clear enough. Please check the post above 
Can you tell us more about what the Arduino will be used for? What you're describing is kind of what a bluetooth headset already does without the Arduino.
He wants the arduino to automatically answer the call, and act as two-way bridge. Phone to arduino, arduino to headset and then back.
HazardsMind:
He wants the arduino to automatically answer the call, and act as two-way bridge. Phone to arduino, arduino to headset and then back.
Kinda Exact. I dont want it automatically answer though. Arduino notifies me about the call and if I want to accept the call, i let it know (maybe a switch or whatever,not on the phone though) and then it connects phone and my headset VIA the ARDUINO.
xkishorx:
HazardsMind:
He wants the arduino to automatically answer the call, and act as two-way bridge. Phone to arduino, arduino to headset and then back.Kinda Exact. I dont want it automatically answer though. Arduino notifies me about the call and if I want to accept the call, i let it know (maybe a switch or whatever,not on the phone though) and then it connects phone and my headset VIA the ARDUINO.
The headset, if it is made to connect to a phone and answer calls, should already do that for you.
HazardsMind:
xkishorx:
HazardsMind:
He wants the arduino to automatically answer the call, and act as two-way bridge. Phone to arduino, arduino to headset and then back.Kinda Exact. I dont want it automatically answer though. Arduino notifies me about the call and if I want to accept the call, i let it know (maybe a switch or whatever,not on the phone though) and then it connects phone and my headset VIA the ARDUINO.
The headset, if it is made to connect to a phone and answer calls, should already do that for you.
Ok I agree. But this is a small part of a big project. So is there a way I can do what I was thinking? A problem I will be facing rightaway is, I may not know if the user is in call if its directly with headset. And with my idea, I could have better flexibility to the whole system. Just wanted to know if its doable, and wanted to know the tips to do.
Thanks a lot already 
Well being that the arduino is going to be acting as a bridge, you might need 2 bluetooth modules, not shields, one to go from the phone to the arduino and the other to relay to the headset. Now this may work, or it may not. Normal arduino bluetooth modules can not handle audio or send and receive from multiple devices.