Shares in MetroPCS Communications rose more than 13 percent at one point this morning after the carrier beat estimates for its first-quarter results and reported new additions tallying 691,602.

“After launching our Wireless for All tax-inclusive plans in early January, we are particularly proud to report record net subscriber additions for the quarter of nearly seven hundred thousand and a notable decrease in churn as compared to the first quarter 2009,” said Chairman, President and CEO Roger Linquist in a statement.

Helped by that Wireless for All plan, MetroPCS’ consolidated subscriber base grew more than 10 percent during the first quarter. Over the past 12 months, it grew its subscriber base by more than 21 percent despite the economy and increased prepaid competition.

MetroPCS is on track to launch its initial 4G LTE network in selected metro areas in the second half of this year, allowing the company to increase its offerings in the smartphone and application categories.

Last week, Sprint reported that it gained a net 348,000 prepaid subscribers in the first quarter, including net additions of 392,000 CDMA customers offset by net losses of 44,000 iDEN customers. Sprint ended the first quarter with a total of 11 million prepaid subscribers, 5.3 million of which are on CDMA and 5.7 million on iDEN.

MetroPCS finished the first quarter with more than 7.3 million subscribers. Shares were trading around $8.87 on heavier than usual volume this morning.

Here are some more first-quarter results for MetroPCS:

• Service revenues for the first quarter came in at $853 million compared with $727 million in the year-ago quarter. Net income was $23 million compared with $44 million in the first quarter last year.

• ARPU was $39.83 in the first quarter compared with $40.40 last year, and churn was down to 3.7 percent compared with 5 percent in the same quarter last year.

• The company’s cost per gross addition (CPGA) of $146.18 for the quarter represents an increase of $11.95 when compared to the prior year’s first quarter and was primarily driven by increased promotional activities in all its metropolitan areas.