Avaya president Lou D'Ambrosio is stepping down from the position for medical reasons after a two year tenure at the top.

Charles Giancarlo, managing director of Avaya's private equity backers Silver Lake, will assume the post until a successor is found. Leadership consultancy Heidrick and Struggles has been tasked with helping find a replacement for D'Ambrosio, who will now adopt an advisory role with the vendor.

D'Ambrosio said: "It has been a true privilege to serve the customers and team of Avaya. I have been blessed to lead a company that has clear technological leadership, a wonderful customer franchise and the most dedicated team in the industry. I will be passionately rooting for Avaya and proudly watching the company thrive."

Silver Lake co-founder Dave Roux added: "Lou has been a guiding force at Avaya during his six-year tenure, the last two as CEO. He has shaped a compelling strategy, built a strong team, and led the company through important technology transitions to market share leadership. We cannot thank Lou enough for his tireless leadership and inspiration and we know he will attack this personal challenge with the same winning spirit and determination he has brought to the toughest business challenges."