Avaya chief resigns, citing health

Avaya's brief statement, dated Monday, didn't elaborate on those medical reasons. D'Ambrosio had led the company for about two years.

Charles Giancarlo, a former high-level executive of Avaya rival Cisco Systems, will run the company full time while Avaya searches for a permanent replacement. Giancarlo left Cisco earlier this year to become a managing director at Silver Lake Partners, a Silicon Valley investment company that took Avaya private last year along with Texas Pacific Group.

D'Ambrosio has also left the company's board but will remain in an advisory role.

Avaya has hired executive search firm Heidrick & Struggles to help Avaya find a replacement for D'Ambrosio. Dave Roux, cofounder of Silver Lake, is the nonexecutive chairman of Avaya.

Before taking the top post at Avaya, D'Ambrosio was president of global sales and marketing, and previously led the company's Global Services business unit. He came to Avaya from IBM, where he worked in a variety of executive roles for 16 years.

Avaya is a major supplier of enterprise voice systems and a key player in unified communications, the set of technologies that is converging voice and data networks along with real-time presence information. Based in Basking Ridge, New Jersey, it has about 19,000 employees.