Microsoft has been officially silent about plans for a successor to its Xbox 360 video-game console, but here’s a telltale sign that things are ramping up behind-the-scenes: The company is boosting security to an unprecedented level in the area of the Redmond campus that is home to the Xbox team, GeekWire has learned.

The company notified employees this week that it will be implementing new physical security measures — limiting employee access at four key Xbox and Interactive Entertainment Business buildings to ensure confidentiality of upcoming products.

It’s the first time Microsoft has taken this step on such a broad scale. The move represents a cultural shift, giving Microsoft’s key consumer products a level of security more along the lines of those implemented by Apple.

Microsoft hasn’t said when its next console is launching, and executives didn’t reference any specific product plans in their communications with employees this week. However, if the company were aiming for a fall 2013 launch of a new console, it would make sense for preliminary systems to start arriving soon for internal use and testing.

The changes will affect Microsoft Studios A, B, C, and D, on the west side of state Route 520, starting early next month with Studio A and rolling out to the other buildings by the end of the month.

Under the new policy, only employees and vendors in Microsoft’s Interactive Entertainment Business or assigned to the buildings will have open access. Other employees and vendors who need to enter the buildings for business reasons will need to go through an online registration process or register at the buildings as visitors, escorted by another employee with access to the buildings. The changes don’t impact the Commons area in the middle of the Xbox campus.

The changes are part of a broader plan to improve Xbox security, including document management. Over the summer, apparent details of the next Xbox version were made public in what was described at the time as the “Mother Of All Microsoft Leaks.”

Microsoft has historically had an open access policy across its Redmond campus, with employees able to visit any building, with rare exception.