Apple Inc. began the sale of the SIM-free (unlocked) models of its latest iPhone 6 and iPhone 6 Plus handsets on its online store in the United States on Tuesday.

The prices of the new unlocked versions of both the handsets are the same as the devices' other unsubsidized versions. The 16GB model of iPhone 6 is priced at $649, while the 64GB and 128GB versions cost $749 and $849, respectively. The unlocked iPhone 6 comes with model number “A1586.”

The price for iPhone 6 Plus starts at $749 for the 16GB version, while 64GB and 128GB configurations of the phone cost $849 and $949, respectively. The unlocked iPhone 6 Plus comes with model number “A1524.”

iPhone6_SIMfree Apple released SIM-free versions of the iPhone 6 and iPhone 6 Plus for U.S. consumers. Photo: Apple

“The unlocked iPhone includes all the features of iPhone but without a wireless contract commitment or a carrier installment plan. You can activate and use the unlocked iPhone on the supported wireless network of your choice, such as AT&T, T-Mobile, Verizon, or Sprint in the United States,” Apple said, on its website.

The SIM-free models of the new iPhones come at a time when rumors are rife that the California-based technology giant could bring back the 4-inch iPhone in 2015, possibly calling it “iPhone 6s mini.”

However, Chinese news website claimed Monday that the company had no plans to go back to the smaller 4-inch form factor for its flagship smartphone this year. Citing sources in Apple’s supply chain, the report said that the company has not started any new “production tasks” for a 4-inch iPhone model.

Last month, Timothy Arcuri, an analyst at Cowen and Company, issued a note to investors, claiming that Apple has been working on a new 4-inch iPhone, which the company could launch in 2015.

In the fourth quarter of 2014, Apple sold 39.3 million units of iPhone 6 and iPhone 6 Plus models, beating estimates of 37.9 million from Goldman Sachs. During the period, the company posted earnings of $8.5 billion or $1.42 per share on $42.1 billion in revenue.

Apple announced on Monday that it will release its financial results for the company’s first fiscal quarter of 2015 on Jan. 27. According to the company, it will be hosting a conference call at 2:00 p.m. PT (5:00 p.m. ET).

The upcoming earnings call is expected to be Apple’s most significant report as it will cover the company’s performance during the three months of holiday shopping period, iDownloadBlog reported.