Updated from 8 a.m.

Juniper ( JNPR) shares jumped 12% Wednesday after the networker won rave reviews for its second-quarter numbers.

The telecom equipment company also boosted third-quarter guidance and set a $250 million stock buyback. But Juniper surprised investors late Tuesday by saying on its conference call that finance chief Marcel Gani would give up his job at the end of the year. Gani will stay with Juniper in a different but otherwise unexplained role, and Juniper didn't name a successor.

For its second quarter ended June 30, the Sunnyvale, Calif., maker of gear for phone networks posted a pro forma profit of $42.7 million, or 8 cents a share. That figure, which excludes certain costs, is up from $13.6 million, or 3 cents a share, a year earlier

The latest-quarter pro forma figures doubled the Wall Street analyst estimate. Using generally accepted accounting principles, the latest quarter showed a loss of $12.6 million, or 2 cents a share.

Revenue surged 86% to $307 million in the latest quarter. That's some 10% north of the analyst consensus estimate shown by Thomson First Call.

"We met our financial objectives, exceeded our goals for integration of the NetScreen acquisition, expanded our partner and channel relationships, all while remaining intensely focused on our customers and their needs for secure high-performance network solutions," CEO Scott Kriens said.

Wall Streeters were amply impressed.

"This was a lot stronger than even some of the optimistic expectations we had seen for the quarter," says American Technology Research analyst Albert Lin, who rates Juniper a buy. "Juniper is lucky to be in IP routing, which is a very hot area both in businesses and in telcos."

Juniper, whose shares have been hit hard this year after a fast start, surged $2.71 to $24.71 in early Wednesday trading.

Higher View

On Tuesday's call with investors, Juniper raised guidance for the current quarter ending in September. Finance chief Gani told analysts the company should report non-GAAP earnings of 11 cents a share on sales somewhere between $356 million and $370 million. Analysts had been looking for a dime profit on $344 million in revenue.

Juniper also expects gross margins to expand to a range between 69% and 70%. Previous gross margins in the second quarter were 68%.

CEO Kriens said the company was ahead of schedule on its integration of NetScreen, an acquisition that closed in April.

'Fabulous'

Tuesday's numbers were quickly celebrated by Wall Street, which had been alert for signs of Juniper's own progress as well as for the health of a key sector. Juniper competes with corporate networking juggernaut Cisco ( CSCO) in the so-called core router segment, selling devices that move data traffic along communications networks. But the company also vies with big phone gear makers Nortel ( NT) and Lucent ( LU) for the affections of the deep-pocketed local phone companies.

Tuesday proved an eventful day across the industry, as Lucent finalized a big network upgrade deal with Verizon Wireless and Nortel said it would have to reconsider its cost structure once again.

For its part, Juniper has seen its stock -- the beneficiary of a wild January rally on the back of a blowout fourth quarter -- sputter and misfire ever since February's NetScreen deal. But late Tuesday, the Juniper fans were back in earnest.

"Come on, they put up $300-plus million and the whisper was $290 million," said one hedge fund manager. "This is good -- in fact, fabulous."