Purchasing iPhone from Apple

If you want to use your current SIM card, so while keeping your current phone number, same carrier, purchase an unlocked iPhone, check here: iPhone - Buying iPhone - Apple

See -> Will my new iPhone be unlocked?

Every iPhone you buy from us online or in an Apple Store is unlocked, with the exception of a few carrier financing options. With an unlocked iPhone, you’re free to go with the carrier of your choice.

If the SIM format is different, visit or contact your carrier and request a replacement SIM card, normally it is free.

Yes, Apple has their own Online Store where you can buy iPhones. You can buy it with one of the Carriers with which Apple cooperates, or choose: Connect to any carrier later.

Shop Apple iPhone:

iPhone - Apple