It’s tough being T-Mobile these days.

After AT&T called off a proposed merger late last year, thanks to intense scrutiny from federal regulators, the company announced fourth quarter earnings today. They said the lack of an iPhone was one of the reasons for a loss of more than 800,000 post-paid customers.

While Sprint joined party in October with the launch of the iPhone 4S, T-Mobile is the last major carrier in the United States without the iPhone. And the company said specifically in the earnings release that not having the phone is causing some issues to the bottom line:

“Sequentially, the decline in branded net contract customers was driven primarily by higher branded contract deactivations as a result of the launch of the iPhone 4S by three nationwide competitors in mid-October.”

The 802,000 customer losses were much higher than the 186,000 in the third quarter of 2011 and 186,000 in the fourth quarter of 2010.

But there is some good news for T-Mobile. After receiving AWS spectrum from AT&T after the merger deal fell through, T-Mobile said it is planning to launch true 4G LTE services in 2013, making it the last carrier in the country to do so.

And since the iPad 3 looks to be sporting LTE when it is probably announced March 7, a LTE iPhone hopefully will be right behind it this fall. So T-Mobile may get to join the iDevice club, eventually.

Are you still holding out for a T-Mobile compatible iPhone?