Will iPhone work in Asian countries?
If you are going to use your iPhone with your own SIM card, You need to activate International roaming from your network provider to work in Asian countries.
If you are going to use your iPhone with an Asian SIM card, you need to unlock the device in prior. You can unlock an iPhone using remote unlocking service. You can get the remote unlocking service for an iPhone from www.superunlockcodes.com This method of unlocking is safe, simple, affordable and quick. This is a permanent unlocking method and doesn’t require a jailbreak too.
Yes and No. The iPhone works on GSM Quad-band (850, 900, 1800, 1900 MHz) So it may work in Asia, depending on where you go, but you’ll have to unlock it first or pay roaming charges via AT&T.\ Your other option is to purchase an iPhone and unlock it. Just know that doing this does void your warranty and performing any future software updates may render the phone useless.