@ezio For most of the 20th century, AT&T was a strictly regulated government monopoly bound by the eponymous consent decree to only work in the field of telephone service while permitting it to have internal subsidiary companies do R&D over mostly whatever they wanted as long as they licensed it out to any company who asked under fair and reasonable terms. For a while this went great, and Bell Labs (their research division) did some of the most important inventions of the 20th century including the transistor, the laser, and Unix. Eventually that last one caught the eye of AT&T management, and they wanted to commercialize it themselves. Thru torturous negotiations with the government, they were allowed to do so in exchange for spinning out all their local telephone operating companies (the so-called "Baby Bells") which thru various incarnations eventually led to most of the phone and internet companies currently operating in the US.