Mr Roberts is a techno-freak. He loves playing with his computers and is lost without his portable laptop. Where other people have to have a cigarette before doing anything else in the morning, he has to check his e-mail. "If you pulled the plug on it, the company would cease to operate," he says. What he does not particularly like doing is travelling around, meeting his staff or holding morale-building parties. Impersonal e-mail, colleagues point out, suits his personality.
MCI was founded by William McGowan as Microwave Communications of America in 1968, and has grown to become one of the biggest telephone carriers in the world.
It had a turnover of $13.3bn last year, and employs 40,000 people. It claims that it has the second-largest digital network in the world, which cost $10bn to install.
Although it had been carrying phone calls before, MCI's big break came in the early 1980s, when Ma Bell, aka AT&T, was broken up by the anti- trust authorities.
Mr McGowan was one of the leaders in the battle to break Ma Bell's power. The so-called Baby Bells took over as regional phone companies, while AT&T itself became a long-distance operator. It soon found itself competing with two other companies, MCI and Sprint.
MCI is still a distant second to AT&T in the long-distance market, with a 17 per cent share of the market, but the gap has been closing. Much of this is due to aggressive marketing - MCI invented the "friends and family" discount scheme now available in Britain, for example. But Mr Roberts has always had ambitions beyond the long-distance phone market.
He has an unashamed aim to run a broadband network that would circle the globe, which is why he sold 20 per cent of the company to BT in 1993. He would also love to break the Baby Bells' lock on local markets. MCI tried to buy a wireless telephony company, Nextel, and has been looking at links with cable companies. It still has money left in the piggy bank after Rupert Murdoch's News Cororation link-up: stand by for more acquisitive e-mail from the energetic Mr Roberts.