The stereotypical "phone rooms," once located in steamy basements, with rows of tables, dozens of phones, and many hoarse volunteers talking at once, still exist among all the major campaigns. But the most dynamic results, those that appear to be shaping this race, are taking place in the quiet comfort of individual homes.

Developments with phone rates and computer programs make this possible. Most cell phones, as well as many home phones, now include some type of unlimited calling or flat per-minute rates. This is critical, not only because volunteers can't afford to spend several dollars per call, but also because candidates would have to record these expenditures as campaign donations.

The other breakthrough involves sophisticated computer programs using data from voter registration forms. When accessed via the Internet, these programs spit out names and phone numbers and also track the calls so that hundreds of volunteers, spread across the country, rarely phone the same person twice.

Howard Dean is often cited as the first major candidate to harness the Internet for his 2004 presidential bid. Dean's Web operation developed what has come to be known as a Netroots campaign - using the Internet to spread messages, raise money, and track voters. The Democratic National Committee now shares these types of data with all candidates, but how each camp uses the data in phone campaigns differs significantly. (The Republicans operate a similar, although somewhat smaller program.)

Senator Obama's operation appears to be the most sophisticated. A volunteer logging on in, say, Florida, can pick an upcoming primary or caucus and receive a list of 20 names and phone numbers for that particular state. The Obama site even asks if the caller wishes to contact "women voters in Wisconsin" or "Spanish-speaking voters in Virginia," and then delivers the appropriate list.

Obama's program also maintains a state-by-state tally of the most successful callers, enabling volunteers to see how their own efforts compare with the most dedicated in their ranks. Many Obama volunteers are completing hundreds of calls per week, an impossible task in a conventional phone room.

Both the Obama and Clinton campaigns furnish a "script" for callers to follow. But while Senator Clinton's outline is general - stressing the war, health care, employment and "accountability" in government - Senator Obama's talking points are tailored to each specific type of call. For the "Wisconsin women," for example, the topics are health care, education, and a woman's right to choose an abortion.

Even with carefully prepared scripts, both campaigns acknowledge there is some peril in allowing volunteers such free reign. Often callers are confronted with questions they can't answer - from Obama's religion to Clinton's finances. Without a precinct captain in the room, or other callers sitting nearby, the volunteers sometimes make up outlandishly incorrect explanations.

Then, too, the freestyle phone programs offer an opportunity for outright cheating: the Obama "volunteer" who tells everyone on his list to vote for Clinton, then marks the computer tally as a "sure" vote for Obama, thus affecting not only the voter but also the campaign's research.

But so far these problems seem scattered. The big picture reflects an electorate, at least on the Democrats' side, which is more engaged in the process than anyone believed possible. The sophistication of the Obama phone campaign is particularly valuable in caucus states, where voters require more complicated instructions to participate effectively.

Both the Obama and Clinton campaigns also use elaborate text-messaging operations to reach cell phone users who have signed up for the program. But while Clinton's messages tend to be generic, Obama's are highly specific, directing voters to proper polling locations by cross-referencing their zip codes.

The Obama campaign's investment in creating the most user-friendly and effective phone program appeals directly to the campaign's younger volunteers, and spreads geometrically as the campaign rolls forward. Volunteers who had no involvement in the campaign until the voting reached their states are now joining the effort to phone voters in other states.

If Obama comes away with the nomination there will be many explanations. But the truth may be that when it came to the first coast-to-coast calling campaign, Hillary Clinton simply dialed the wrong number.