The group is on the verge of announcing its decision on the review, which is understood to include four agencies.
Incumbent Hill & Knowlton is believed to be competing against Citigate Technology, Bite Communications and Weber Shandwick for the work.
Microsoft Business Solutions PR manager Sarah Perkins said presentations had taken place and that a decision was expected imminently.
She confirmed the pitch was being conducted separately from Microsoft's main agency roster: 'Microsoft has a roster of agencies, but Business Solutions is quite a different brand in terms of the PR approach.'
The Business Solutions operation, which focuses on services specifically designed for SMEs, is one of the firm's most recently formed initiatives, housing two main acquisitions: Great Plains, which Microsoft bought two years ago, and Navision, taken over last July.
H&K won the combined brief last July over Navision's incumbent Citigate.
Perkins, appointed last year from Berkeley PR, said the review is part of a plan to better integrate Navision and Great Plains. The brief will focus on B2B communications, targeting the trade press.