Michael Robertson seems to enjoy trying to shake up the powers that be, as he did in music with MP3.com and in computer software with Lindows (now Linspire). Now, he has jumped into the surging field of Internet telephony with Gizmo, the working name for a voice-over-Internet protocol program from his latest venture, SIPphone. Robertson, naturally, thinks the more open nature of Gizmo will win over millions of people who have been using Skype, the runaway hit in free Internet telephony. Gizmo uses the open Session Initiation Protocol vs. Skype's proprietary technology.

With 41 million users, up to 3 million making calls at any one time, and some promising revenue opportunities such as the ability to call regular phones, Skype clearly isn't hurting yet. But Gizmo's challenge just goes to show that these days, more than ever, there's a vanishingly brief window of opportunity for upstarts--especially when all these new technologies help us users get together to keep companies honest.

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