About the unlocked iPhone
The unlocked iPhone includes all the features of iPhone but without a wireless contract commitment. You can activate and use iPhone on the supported GSM wireless network of your choice. The unlocked iPhone 6s or iPhone 6s Plus will not work with CDMA-based carriers. An unlocked iPhone 6s or iPhone 6s Plus may not support LTE networks in all other countries; contact service providers for details.
If you don’t want a multiyear service contract, or if you prefer to use a local carrier when traveling abroad, the unlocked iPhone is the best choice. It does not come with a nano-SIM card, so you’ll need to get one from any supported GSM carrier worldwide. To start using it, simply insert an activated SIM card from a compatible network. Then turn on your iPhone and follow the onscreen instructions to set it up.