Social.im, a desktop IM client built as an application on the Facebook Platform, has been acquired by mobile VOIP company iSkoot, TechCrunch reports. iSkoot likely plans to use Social.im’s client to expand its VOIP service inside social networks. Terms of the deal were not disclosed.

Before Facebook launched Facebook Chat, Social.im looked like it could build a meaningful service on top of the Facebook Platform. However, Facebook deemed chat too central to its communication platform vision, and Social.im was left competing with the Platform it largely depended on.

Despite a fantanstic angel investment team including Facebook board member and original investor Peter Thiel, Aydin Senkut (of Google and now Felicis Ventures), and Georges Harik, it looks like Social.im saw the writing on the wall and found a buyer that could use what it had built (a well functioning IM client connected to the Facebook Platform) to work toward a different goal.