Click on the blue link to find an Apple Authorized Service Provider next to your place, or contact your carrier to get the phone serviced.
iPhone Authorized Service Provider
The iPhone support site has troubleshooting articles to help you solve your iPhone issue on your own. If you have reviewed those articles and still need service for your iPhone, you can contact an iPhone Authorized Service Provider or contact Apple if you purchased your iPhone directly from Apple. Note: There may be a fee for diagnostic service. Please do not send any accessories with your iPhone because they will not be returned to you.
copied from Service Answer Center - iPhone /India
In case you bought your iPhone in another country, you'll have to bring it back to the country of purchase to get it serviced. The warranty is only valid in the country of purchase.