Infonetics Research said worldwide TDM (time division multiplexing) used in traditional circuit switching is expected to drop 88 percent while IP PBX revenue should jump 82 percent in the 2004 to 2009 timeframe. The report is scheduled for release Tuesday, Infonetics Research said.

"The PBX market came in at our expectations in 2005, and from a global perspective is doing very well," said Matthias Machowinski, Infonetics directing analyst, in a statement. "Worldwide revenue growth accelerated in 2005, although it's mostly coming from EMEA, Asia Pacific, and CALA. North America lost revenue share in 2005 as things slowed down here, showing just 4 percent revenue growth for the year."

In 2005, combined TDM and IP PBX systems revenue reached $8.1 billion, a 12 percent increase over 2004.

In the booming IP PBX market a horse race has broken out among the three top providers with Nortel Networks leading Avaya and Cisco by a slim margin, Infonetics said. Cisco, however, leads the IP phone category with a 42 percent unit market share.