One technology promises to harness the power of the Internet for voice communications.
Its competitor has been around for a century, and has an industry shorthand that needs two adjectives -- "plain old telephone service" -- to describe just how boring it is.
The battle between the two is expected to heat up in 2005, as we move further into the much-hyped "Year of the Internet Phone."
But even if the most optimistic predictions come to pass, industry analysts say, plain-old telephone lines will still have a tight grip on much of the market.
Still, even if it doesn't take over the phone market, Internet telephony, or VOIP (voice-over-Internet protocol), seems poised to make inroads in the United States, thanks to growing numbers of high-speed Internet connections and companies pushing Internet phone services.
James Jeffries said he signed up for VOIP service from Vonage because it was the first competitor to Sprint Corp. in his rural Pennsylvania town.
Analysts figure that the number of home VOIP lines in the United States was roughly 1 million at the end of 2004, a drop in an ocean compared with about 160 million landline and 170 million cellular phone subscribers.
But some estimates say VOIP subscribers could triple this year, thanks largely to cable company campaigns to sign up phone customers, and hit 20 million by 2008.
Other countries that have more widespread broadband use have seen faster VOIP growth, with Japan's Yahoo Broadband the largest provider so far at 4.4 million VOIP lines.
VOIP companies do not always offer phone numbers in every area code, and may not have numbers available in popular area codes such as New York's 212.
Many cable companies use Sprint's landline network as a backbone, allowing them to offer 911 service, and usually offer installation.