posted a 77% gain in first-quarter earnings on a 12% sales rise.

The Swedish maker of wireless infrastructure gear earned 4.6 billion kronor, or $654 million, in the quarter ended March 31. That's up from the year-ago $371 million, as gross margin rose to 48.5% and operating margin hit 21%.

Sales rose 17% from a year ago on a constant-currency basis, hitting $4.48 billion and beating the $4.34 billion Thomson First Call analyst consensus estimate. The company called the gain "encouraging" but noted its weak start last year.

Sales in Western Europe rose 26% in the latest quarter, while those in Central Europe, Middle East and Africa added 20%. Asia Pacific was up just 4%, though, and North America fell 24% as wireless carriers began consolidating last year. Ericsson said it believed sales would pick up as the third-generation network rollout begins later this year.

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, which helped to stoke Thursday's rally by predicting a strong rise in 2005 wireless sales, Ericsson said it's maintaining a conservative view on the market. "For 2005 we maintain our view that the global mobile systems market will show slight growth compared to 2004," the company said Friday.

Ericsson closed Thursday at $30.20.