The way some Indians address their friends indicates the area they have mostly likely spent their childhood/college time. Take for example the following addresses:
From my non-scientific analysis, I have so far identified some of the places these are most commonly used. 'maga' is from Karnataka where maga literarily means son. Sentences ending with 're' are from Mumbai. Usually people using 'di' are from Tamilnadu while yaar is a commonly used in North India.
So when you hear someone talk to their friends, you can atleast make out where they have most likely been brought up in. There is no gaurantee however as people may want to sometimes portray a certain image and may use a certain style to be identified with.