Google could be your phone company.

This possibility begins with the broadcast signals that once carried hokey sitcoms (Green Acres! The Munsters!) to TV rabbit ears. Those signals are about to become useless as sets go digital and the government prepares to auction off the old analog UHF spectrum in January. The odds-on favorite to win is Google, which has conditionally offered to meet the $4.6 billion opening bid. The auction will take the price much higher.

Google won’t say what it would do with the spectrum, but it’s expected to turn its acquisition into a nationwide wireless internet, thereby pureeing existing telecom business models. It’s easy to imagine Google offering a free, ad-based wireless voice-and-data service in exchange for, say, your turning on your phone’s G.P.S. location tracker so the company can serve you ads for the Krispy Kreme shop you’re about to pass. What’s another hunk of privacy lost if it saves you some dough?

As Greg Butz, a senior vice president at cable operator Comcast, which is also eyeing the UHF spectrum, notes, “Customers are looking for someone to step in and redefine why they’re spending $120 a month on wireless.”

Just a whiff of such a future has created consternation in one of the most important business sectors on the planet. The big cellular incumbents—AT&T, Verizon Wireless, Sprint—could be toast. The cell companies have spent tens of billions of dollars building their networks. AT&T is $54 billion in debt; Verizon, $29 billion. Even a slight erosion of their customer base and pricing plans would hurt them. They could find themselves in that dangerous place where I.B.M. was in the early 1990s and where General Motors is now: with overpriced products and an overburdened legacy, unable to respond to disruption from below.

Google won’t be the only interloper. We are witnessing a communications big bang—a moment when the industry explodes into shards and re-creates our talking and texting universe. Much of this has to do with the fairly recent advent of cheap, reliable WiFi and with our having reached the tipping point at which a significant portion of the population wants to be online everywhere, all the time. EBay’s Skype is starting to build thousands of WiFi hotspots, which will make it, in effect, a wireless phone company. Cities like Philadelphia are building quasi-public municipal WiFi networks, much as they once built sewers. As of August, 415 cities had WiFi networks in place, according to Muni Wireless. “Somehow, along the way, telecom has become almost sexy,” says Cisco Systems senior vice president Don Proctor, who’s giddy about the prospect of selling arms to all the industry’s combatants.

New devices will act as agitators. The iPhone is an early example. Yes, it’s technically locked in to AT&T’s cellular network for calls. But iPhones also have WiFi, which means that even if you’re not as savvy as that 17-year-old who figured out how to unlock his iPhone, they can be rigged to make free calls on Skype or Jajah. Apple’s phone is not the only one with WiFi capability. About 75 million dual-mode cellular/WiFi phones of various makes will be sold worldwide this year, says Infonetics Research. By 2010, the total will be 285 million.

Motorola, Cisco, Nokia, and others are experimenting with dual-mode phones that can smoothly hand off a call from one network to another. So if Jerry from accounting calls while you’re in the car, you’ll start talking over a cell network; and when you arrive at the office, the call will switch to your company’s much cheaper corporate WiFi. This may foil your plan to get rid of Jerry by saying you’re about to lose his call, but innovation often comes with a price.

The next step is phones that work on any wireless network, the way any pot works on any stove. Google is pushing to have these so-called open phones work on the UHF spectrum, which would help end the practice of binding phones to certain networks and handcuffing customers to contracts. In other words, if the new spectrum opens the door for unlocked phones, then wireless companies could be forced to change the way they manipulate consumers and handset makers. It’s a change that Kevin Martin, the Federal Communications Commission chairman, wants. “There would be some real consumer savings on the wireless side,” Martin said in an interview early this year. More than that, it’s a transformation most consumers would like.

Put it all together—the fear of Google, the new spectrum, new entrants, open phones—and it’s likely we’ll have a very different telecom industry a decade from now. As with today’s media business, in which CBS vies with YouTube, the communications sector will be a blend of old companies, brash newcomers like Google, and crazy startups with nothing to lose. For a while, this mess could be rough on users. At some moment in the not-so-distant future, you might stand on a street corner, pull out your wireless gadget, and be forced to decide how to make your call: on one of several cell networks, the city WiFi, Skype WiFi, or an unsecured wireless connection from a nearby condo. Some options may be bad but cheap, others good but expensive. Your choice might depend on whether your call is to your daughter (needs good quality) or to Jerry, to answer his questions about that expense report (needs bad quality).

Eventually, the whole communication mess is supposed to be sorted out in our favor. People who work in technology say we’ll get a wireless phone that can work on any network in any country and has our office and private numbers, email, broadband internet access, G.P.S., I.M., and features like Helio’s Buddy Beacon. If friends have their Buddy Beacons on, their location will show up on your phone’s map and you’ll know when they’re clustered at the Pine Lounge.

By 2015, Google might have built out its network and destroyed the cell companies’ way of doing business. This is what Google is good at. Look at how it upended online maps, email, and the internet-advertising industry. Once the juggernaut conquers communications, it will no doubt move on to disrupt some other industry that’s fundamental to Western society in the 21st century by giving away yet another commodity. Like free Google coffee.