It's that time of year again, when a new iPhone (or iPhones) releases, and all the big carriers begin scrambling to announce the best deal just to keep existing customers and even steal some new ones.Sprint is one such carrier. When the new iPhones launch on 20 September, Sprint says it will slash $100 from the iPhone 5S and iPhone 5C for new US customers willing to port their number from a competing carrier. The deal will actually work for any smartphone, but it's interesting - and unusual - that Sprint will allow it to work for Apple's latest handsets too.Read: Where to trade-in your old iPhone in USWith $100 taken off the top, new Sprint customers can get a 16GB iPhone 5C free on-contract, while the iPhone 5S will cost just $99.99. That's one of the best deals available, though US carrier T-Mobile, has similar pricing.\u00a0T-Mobile announced it would offer the iPhone 5C free and the iPhone 5S for $99 down. But customers will need to enrol in T-Mobile's Jump upgrade program. Unlike T-Mobile, Sprint's deal comes with immediate savings and gratification as long as a customer brings their phone number from a rival and signs a two-year agreement.Not bad, right? Happy iPhone shopping!