MetroPCS Communications reported adding 960,000 gross subscribers in the first quarter, a 15% rise year-over-year in gross customer additions. The flat rate, no-contract carrier said it ended Q1 with approximately 4.4 million subscribers, including net additions during the quarter of about 452,000 subscribers. The company said churn was flat at 4%.

The carrier said it was helped by expanded markets; it added service in the Los Angeles market during Q3 2007, and it said it expects growth to continue as it entered two new markets at the end of Q1: Las Vegas on March 28 and Bakersfield, Calif., on March 31.

“Growth in Los Angeles continued to accelerate throughout the first quarter driven by ongoing expansion of our service footprint and our distribution network within the Los Angeles metropolitan area…We also continue to benefit from the ongoing landline replacement trend in the United States,” said Roger Linquist, MetroPCS’ chairman, president and CEO, in a statement.

“At the end of the first quarter, our consolidated subscriber base was over 4.4 million, representing 30% growth when compared to the first quarter of 2007. While the fourth and first calendar quarters have traditionally represented our strongest seasonal quarters, we believe our results are very strong given the overall challenging macro-economic environment in the United States.”