Davies, a former Cohn & Wolfe director, was unavailable for comment. But retained corporate agency Edelman said Davies would work alongside Campbell – who started this week – for at least three months.
Campbell, who oversees a team of six, reports to Microsoft business and marketing officer Nick Barley. Her primary focus is on tech and business comms, with a brief to integrate PR and marketing.
Microsoft is also recruiting for a 'UK technology audience PR manager', to replace analyst relations and PR manager Tracey Pretorius. She served as Davies's number two until taking a global role in the US to communicate Microsoft's strategy for dealing with rivals (PRWeek, 21 Oct 2005).
Last September the company regrouped its seven divisions into three arms – products and services, business, and entertainment and devices. The restructure aimed to achieve greater efficiency and address criticism that it had become unwieldy.
Microsoft was last month forced to delay its eagerly awaited Windows Vista – the first overhaul of its operating system since XP five years ago. The consumer version has now been slated for January 2007.
Campbell said: 'The next year will see the launch of Vista and other significant product releases, so ensuring we communicate in a relevant and compelling way is a challenge.'
Before Siebel, which she joined in 2003, she was director of communications at Internet Incubator and corporate communications director at Oracle Corporation UK. In 1993 she became PR manager at Bull Information Systems.
Oracle bought rival Siebel for $5.8bn (£3.3bn) in September 2005. Siebel would not comment on whether it intended to recruit for Campbell's replacement.
Microsoft retains Edelman as its corporate agency and uses Weber Shandwick and Inferno Communications for technology PR work. The Red Consultancy handles PR for the company's Xbox 360 games console.