In a run up to its new mobile subscription models that come into effect from 2013, U.S. carrier T-Mobile has begun its "Zero Down Sale," where the hottest 4G smartphones will be available for a mere $0!

The T-Mobile sale began on Friday, Dec. 21 in stores and will wrap up on Monday, Dec. 31. The U.S. carrier is offering some of the most wanted 4G smartphones of the year for free with no down payment.

"Hurry in and take home a 4G smartphone with no down payment-even the Samsung Galaxy S^® III. Plus, get the most out of your new phone with our Unlimited Nationwide 4G Data plan," notes T-Mobile.

In case you're wondering why T-Mobile has taken the "free phones" route and is giving such a mammoth discount, it is because the carrier is set to change its current subsidy-based business model from 2013, which means that it will no longer offer phones on contract from next year.

The offer is valid for select devices only after a mail-in rebate, on a new two-year agreement, which means that consumers will have to pay for the value plan. Additionally, potential buyers will also have to dole out $20 per month for the next 20 months for T-Mobile's Equipment Installment Plan (EIP).

Though the best-selling Galaxy S3 from Samsung is included in the "free phones" list, the Galaxy Note 2 and the elusive Google Nexus 4, which sold out within a few hours of its release in the UK and the U.S. are notably missing from the line-up.

Both the Galaxy Note 2 and Galaxy Tab 2 10.1 can be procured for a down payment of $99.99 and the Nexus 4, per an Android Police report, was previously listed as well but has now sold out.

The impressive list of free smartphones on offer also includes latest devices like the Windows-powered HTC 8X and Nokia Lumia 810. The complete list of smartphones that are a part of the 'Zero Down Sale' can be viewed here.

With so many fantastic smartphones on offer, which device from T-Mobile would you opt for?