Two things puzzle me about iPhones:
1) why people who live outside the US want to buy a phone in the US, instead of their home country. They'll have no support service and no warranty. Just to save a few dollars? Seems penny-wise and pound-foolish. Apple's phone is the most expensive to start with. If you want to save money, buy a cheaper phone, not an Apple.
2) why anyone who wants an unlocked iPhone 5s for international use buys one from a carrier, rather than directly from Apple. Decide whether you need CDMA or GSM (almost certainly GSM for international use). Then pay full price and get an unlocked phone from Apple. Buying through a carrier just guarantees there's going to be a third party involved, which complicates matters of compatibility, service, and warranty. If you need to finance the cost over two years, look for alternatives (a bank loan, a loan from a friend or relative, save your money until you have enough, etc.)
Thanks...I feel much better now!