Buy an unlocked phone , this way you can use it anywhere in the world , given that the phone supports all the frequency bands. Most of the recently released smartphone are capable of this.
Or else if you are buying a smartphone from at&t or anyone else with locked state , you can later on purchase or obtain unlock codes in order to use the phone with other carriers as well.
For instance , I am currently using an unlocked at&t phone bought from US. Even my previous one was at&t unlocked.
No problem.Thanks for the info mate..!!!
My friend is Coming to India next month from US,so i'm planning to get nexus 5 or lg G2..Do they work in india or should i need to unlock it to get it worked ? And how do i unlock phone or to be done ? Need some details..