I'll admit this one made me laugh when I saw it, and I didn't quite believe it. I had kind of a "what will they think of next" reaction, but after looking into it a bit, it does seem promising. The premise of JAJAH @Call is simple - you just need to sign up for their service (the person you're calling needs to be signed up as well) and then send a tweet to call them. So if I wanted to call Kevin I could easily tweet @call @crackberrykevin and I'd be connected. It supposedly works from any Twitter client (desktop, BlackBerry, text etc) without a hitch. From what I understand the calls are free for two minutes, and there are fees after that (the full pricing list varies by location). For more information or to sign up, check out jajah.com. If you test out the service be sure to leave a comment and let us know how it works.