Digium CEO Mark Spencer has spent a lot of time over the past few years politely turning aside the advances of VCs but he has finally caved in by taking $13.8-million from Matrix Partners. For open-source supporters, it's another sign the "movement" has gone legit. Of course, Red Hat buying JBoss for $420-million earlier this year was a pretty good sign that open source was entering the mainstream. So why did Spencer, who I once described as the Linus Torvalds of IP-PBX, taking the cash? Well, it's not exactly clear because he says Digium, which oversees development of Asterisk and sells related hardware and services, doesn't really need it. In talking with Spencer, it sounds like he's aware of the growing competition from small and larger rivals, and wants to make sure Digium has the cash it needs to strategically respond. "This is really about trying to make sure we do the right things going forward," he said. "When you start out, there is a lot of room when you are making a new industry to make some mistakes and get away with it. As you get farther along and get people on your tail and paying attention to what you are doing, you have a lot less room, and we need to make sure we preserve a lot of the things we have done that are good." Spencer said the deal with Matrix, which financed JBoss, is not a traditional VC arrangement. While declining to provide a lot of details, he said it "preserves the spirit of the company and leave the company in control" - nice terms if you can get them. Of course, Digium had some clout given it's been profitable since 2002 and growing revenue by 100% a year.Note: For more, check Red Herring and BusinessWeek.