As of Friday, April 5, iPhone 5 pre-orders on T-Mobile USA are now live ahead of the big launch scheduled for April 12.

T-Mobile USA is the nation's fourth largest carrier, and this is the first time that T-Mobile is offering an iPhone on its network. Nearly two million "unofficial" iPhones are currently running on T-Mobile's 3G network, but the telecom just recently signed a deal with Apple to carry the smartphone. It is the last of the "Big Four" U.S. carriers to do so.

In line with its announcement last week, T-Mobile now started taking pre-orders for the iPhone 5. The 16GB model starts at $99.99 for customers who opt for a subsequent monthly-payment plan of $20 per month for two years. Otherwise, the handset is available for $579 upfront. Under its new "Uncarrier" campaign, T-Mobile drops phone subsidies in exchange for lower monthly rates.

On Thursday, April 4, T-Mobile reported preliminary numbers for the first quarter of 2013, suggesting that it picked up 579,000 new users. The increase may be an early response to the telecom's new "Uncarrier" campaign.

When Apple's latest smartphone hits store shelves on April 12, T-Mobile customers will be able to use the iPhone 5 to access the carrier's new LTE network in seven U.S. markets: Kansas City, Kansas, Houston, Texas, Las Vegas, Nevada, Phoenix, Arizona, San Jose, California and Washington D.C.

If recent speculation turns out to be true, T-Mobile may also be closing a merger deal with MetroPCS soon, boosting the number of addressable subscribers from 33 million to 42 million. This, in turn, would make the iPhone 5 even more widely available, and Apple's entrance on T-Mobile will bear even more significance.

T-Mobile now lists the iPhone 5 available in black and white in all three configurations — 16GB, 32GB and 64GB — with downpayments ranging from $99.99 for the 16GB model to $299.99 for the 64GB variant. For more details about the phone and the carrier's pricing options, visit T-Mobile's website. With this new addition, T-Mobile is no longer the last in line, The iPhone finally hits the network, and what better debut than with the latest model?