After two years of declining product orders and a flagging stock price, Morrisville technology company Tekelec announced this morning that CEO Frank Plastina has immediately resigned.

The telecom gear-maker gave no reason for Plastina's departure, effective yesterday, after five years at the helm. Plastina, 48, also stepped down as a member of the company's board of directors.

Tekelec's chief financial officer, Greg Rush, said the board of directors felt Plastina had taken the company in the right direction but also felt it was time to take the company to the next level in developing and selling next-generation telecommunications technology.

Investors reacted positively to the news, pushing up Tekelec's stock's value 7.5 percent by early afternoon, to $12.92 a share. The stock had been down about 23 percent in the past year.

Tekelec this morning reported weaker quarterly results and lowered its financial outlook for the third time this year, a sign that the slower global economy continues to hurt demand for its telecommunications equipment.

The Morrisville-based company sells products and services to cell phone carriers and other customers, including equipment that starts and ends phone calls. It also helps carriers manage traffic on mobile networks.

Revenue for the quarter that ended Sept. 30 fell to $108.3 million, down 6 percent from a year earlier, led by a decline in sales of older equipment in emerging markets. The company also posted a small loss, reversing a $9.4 million profit a year ago.