Method to identify a mobile call, from where it come from?

  There is a specific no/code for each zone..if you know the code you can trace the location.

Viz: +91 is the code for India. This is International Number Plan (INP) maintained by ITD [For more :http://www.numberingplans.com/]. And India has also a National Number Plan (NNP) maintained by TRAI.

You also locate online the area from where it come. 

http://www.numberingplans.com/?page=analysis&sub=phonenr

http://www.internet4mobile.com/mobile_number_information.aspx

http://mobilenumberlocator.in/mobile-number-locator.php

http://www.mobilenumbertracker.com/default.aspx

There also some software which enable you to trace offline.