If you are looking to purchase unlocked versions of the iPhone 6 and iPhone 6 Plus, here is some good news: Apple has begun selling the SIM-free models in the US through its retail outlets as well as its online store.

Up until now, customers in the US could purchase unlocked versions of the devices only through T-Mobile -- to activate the smartphone, you're either required to visit an Apple store or contact the carrier. Once done, you can just replace the T-Mobile SIM with that from any other carrier of your choice.

Today's change, however, makes the process a bit easy, as it does away with the need for the activation steps mentioned above. All you need to do is buy a nano-SIM from a carrier that supports the latest iPhones.

The SIM-free iPhone 6 ranges from $649 to $849 depending on storage choices (16GB, 64GB, or 128GB), while the iPhone 6 Plus ranges from $749 to $949.

The iPhone 6 and iPhone 6 Plus launched last September in the US as well as many other countries. A few days later, Apple announced that the company sold more than 10 million iPhones over the launch weekend, eclipsing the previous record of nine million with the 2013 launch of iPhone 5s and 5c.