Hi Vasudev,
                 No need to go to phone unlocking shop.Nowadays you can unlock your iPhone4s  from home with a help of online unlocking service provider There are several ways to unlock Iphone. According to me remote unlocking is the best way to unlock Iphone.There are many online providers who provide this service .Let me suggest a site where i used to get my mobile phone unlocked http://www.wickedunlock.com/apple-iphone-4s/rs16wp9/   .If you want you can try them