After tilting at powerful record labels and Microsoft Corp., MP3.com founder Michael Robertson is challenging the telecommunications industry with a venture that offers unlimited free phone calls.
SIPphone Inc. of San Diego, which Robertson announced Wednesday, has begun selling specialized telephones that transmit calls through a user's high-speed Internet connection.
The catch is, the devices can call only other Internet-based phones in the company's directory and toll-free numbers.
That's only a tiny fraction of the phones currently in use around the world. Nevertheless, Robertson contends his company can spur the development of a much larger market by offering low-cost, easy-to-use Internet phones.
Robertson, who funded SIPphone personally, said the new company springs from the same logic that inspired his two previous efforts -- MP3.com, which allowed musicians to distribute their songs independently of the record labels, and Lindows.com Inc., which developed an easy-to-use version of the Linux operating system for personal computers.