Microsoft (NSDQ: MSFT), which has been quiet on the deal front for several years now, is reportedly set to change that in a big way, picking up Skype for $7 billion-plus. The Wall Street Journal (NSDQ: NWS) cites sources who say a deal could be announced tomorrow. It would be the largest acquisition in Microsoft’s history, topping the company’s $6.3 billion purchase of aQuantive in mid-2007, which has arguably not paid off.

The WSJ article lists a number of general reasons why Microsoft is interested in the VOIP service: It would give the company a major consumer-facing internet brand, it could boost Microsoft’s own enterprise-focused Lync communications platform, and it could possibly somehow be integrated with its Windows Phone 7 operating system. Skype had $860 million in sales in 2010.

Skype has repeatedly changed hands in recent years. EBay, which purchased the company for $2.6 billion in 2005, sold it back in 2009 to the company’s founders, as well as VC firms Silver Lake Partners and Andreessen Horowitz in a deal that valued the company at $1.9 billion. (An aside: EBay still holds a 35 percent stake in the company, so if Microsoft really is paying as much as $7 billion for Skype, the e-commerce company should just about make all of its money back).

Last summer, Skype filed to go public, although in recent weeks there were reports that the company was considering selling itself to Facebook or Google (NSDQ: GOOG) instead. Microsoft was considered to be a long-shot suitor with GigaOm reporting Sunday that Microsoft was in fact in the mix too.