Vodafone's chief technology officer Steve Pusey is retiring from the company on 31 July 2015, according to a statement on Thursday.Pusey has been with the group for eight years during which he has led the global expansion of Vodafone's 3G services and the launch of 4G in 15 countries.Johan Wibergh, who is currently executive vice president and head of the Networks segment at Ericsson, will succeed Pusey.