A note: the telecom industry is one arena where there are fewer and fewer competitors. Sprint and Nextel are together, as is AT&T and SBC as well as MCI and Verizon. Six big names reduced to three in the span of a year, with less choice for consumers.
Um, there never should have been more than one company in local and long distance service to begin with. One of the government's biggest mistakes was breaking up the old AT&T Bell System in 1984. It was the most efficient system in the world at the time. Hopefully, AT&T will merge with BellSouth, then Qwest, and finally Verizon to create a new Bell System for the 21st century.
There would still be competition, as the cable companies like Comcast and Cox are starting to provide phone service as well.
NOTE: that is the only case where I feel there should be a monopoly in a single branch of industry.