T-Mobile's losses mount as No.4 carriers pushes subscriber gains

T-Mobile US Inc., the fourth-largest U.S. wireless carrier, reported a net loss for a third consecutive quarter as subscriber gains, driven by its cheaper service plans, resulted in higher costs.

The net loss for the fourth quarter totaled $20 million, the Bellevue, Washington-based company said today in a filing. T-Mobile posted a third-quarter loss of $36 million and a second-quarter loss of $16 million.

T-Mobile is working to lure customers by challenging the industry's use of long-term contracts, discounted phones and international roaming rates. Last month, the company started offering as much as $450 to people who switch service from rivals such as AT&T Inc. T-Mobile, which merged with MetroPCS last year, added 869,000 monthly customers last quarter, topping the 791,000 average of analysts' estimates.

While customer additions have increased, the average bill size has shrunk. T-Mobile's average phone bill for monthly subscribers shrank about 2.9 percent to $50.70 from $52.20 in the third quarter. Analysts had projected $51.06, according to a survey of eight analysts by Bloomberg.

T-Mobile rose 0.9 percent to $32.31 yesterday in New York. The shares have lost about 4 percent this year.