Brian McFadden, chief research officer, and Sue Spradley, president of global services and operations, were officially replaced on Monday, the spokeswoman confirmed today. "The company thanks them for their years of service," she said.

McFadden, who has served Nortel for 28 years, was replaced in the interim by Peter Carbone, vice president and chief architect at Nortel. Spradley, who has been with the company for 18 years, is being replaced for now by David Downing, vice president of global services and operations, and John Haydon, vice president of global supply chain, the spokeswoman said. No other strategic hirings or replacements have been made, she said.

Nortel brought in Mike Zafirovski as CEO on Nov. 15, replacing William Owens. Owens oversaw a rough transition at the company, which fired several top executives after auditors found that Nortel had to restate earnings from 2001 to 2003.

Even as this week's departures were made public, Nortel was touting its top position in sales of IP voice switches in North America for the third quarter, as reported by Infonetics Research in Boston. Infonetics ranked Avaya Inc. second, followed closely by Cisco Systems Inc.

A Nortel spokesman noted that hybrid voice switches, which combine the capabilities of circuit- and IP-switched systems, have outsold pure IP switches, which Cisco makes. He added that the sales of hybrids are a validation of "Nortel's strategy of providing choice for customers as they looking to migrate to IP systems."