iPhone Warranty

My friend gifted me an iPhone 5 which he bought from Dubai Shopping festival(UAE).It was factory unlocked but I found an AT&T nano sim inside.Now the lock switch is not working properly and I wish to take it to a service centre.I live in India.SO the fix is that the phone was bought from UAE,but it is a US model and I live in India.Its warranty period is not yet over.Can I avail some sort of warranty.(A1428)