At long last, it appears that T-Mobile USA will become the last of the "Big 4" wireless carriers in the country to carry Apple products. Deutsche Telekom, the parent company of T-Mobile USA, made an announcement today that the carrier will begin selling iPhones in 2013.

To make its network iPhone-friendly, T-Mobile is investing in making its existing 3G network compatible with iPhones and will be deploying a next-generation LTE network in 2013. The company is also actively pursuing current iPhone owners to unlock their devices and move to the magenta network.

All of T-Mobile's US network upgrades are going to cost a pretty penny -- All Things D reports that the company will spend $4.7 billion on capital expenditures in 2013, and about $3 billion in 2014 and 2015. The company currently spends an average of about $2.7 billion a year.

There's no word on whether or not T-Mobile USA will be selling the iPad, but with all of the other carriers now hosting Apple's tablet, it's likely that the company will pursue the option. All Things D also notes that adding the iPhone will add to T-Mobile USA's cost spent in acquiring new customers, as the iPhone usually comes with a "high subsidy for contract plans."