Home telephones are finally getting smart.

A new generation of home phone systems promises to make life a little easier, at least for heavy phone users, by bringing together desk phones, cordless phones and answering machines in one package. Such systems can offer new features, such as room monitoring and walkie-talkie communication, that previously weren't possible without first acquiring a shelf full of hardware.

The first example of such a system, in my view, is the new Siemens Gigaset 2420, a $399 device that brings together a conventional two-line desk phone, a long-range cordless phone and a digital answering machine with 26 minutes of voice storage (www.siemenscordless.com).

What makes the Gigaset stand out is expandability. You can install up to eight cordless handsets, at about $150 each, that work with the desk phone "base station." Through an intercom mode, these handsets can talk to the base station or to each other without tying up a phone line -- a big benefit for small businesses and busy families.

Siemens AG, a large manufacturer of telecommunications equipment based in Germany, isn't a household name in the United States, but the phones are now available in stores including Office Depot.

Cordless phones, for those who haven't been paying much attention, have gone through stunning improvements in the past few years.

The original cordless models that debuted back in the 1980s used frequencies ranging from 43 megahertz to 49 megahertz, and are known today as 43-49 or 25-channel phones. These frequencies are easily disrupted by anything from garage door openers to microwave ovens, and the range is so limited that it's often difficult to get a connection when you leave the room where the phone's base station is located.

A big step forward came in 1992 with the introduction of cordless phones operating at 900 MHz. Disruptions almost disappear at this higher frequency, and range grew sufficiently to cover a typical house and the surrounding yard. Some newer 900-MHz phones use digital transmission instead of analog, offering slightly greater range and clarity.

Yet another upgrade came last year with 2.4 gigahertz cordless phones, running at an even higher frequency offering yet more range.

Today, entry-level 900 MHz phones are $50 to $100; older 25-channel phones, which I'd avoid unless you're on a starvation budget, are generally under $50. The fanciest digital 900 MHz phones are up around $150 to $200, while 2.4 GHz models are about $250.

Of course, prices will come down over time. In two or three years, I expect $29 cordless phones will run at 900 MHz and 2.4 GHz phones will be well under $100.

Which brings me back to the Gigaset. As the name implies, this is a 2.4 GHz system. In my informal testing -- walking down the street while talking on the handset -- I found the Gigaset slightly exceeded a high-end 900 MHz phone I reviewed two years ago. That meant I could go about two city blocks on a flat street with the Gigaset, and about one block when moving up or down a hill.

The charcoal-colored Gigaset base station looks like a familiar office phone complete with a regular "corded" handset; the only sign that it communicates with cordless handsets is a stubby, inch-long antenna sticking out of the right side. An array of buttons allows the user to place or receive calls on two lines, listen to answering-machine messages and program the system's many features through a small display screen.

The $399 Gigaset package also includes one cordless handset and charger. Additional handsets are $129, and additional chargers are $19.

The slim six-ounce handset, in matching charcoal, has no external antenna and resembles a pocket-size cellular phone more than the typical clunky cordless receiver. I appreciate this reduction in size and weight, but some users might actually miss the bulk -- especially if they want to cradle the phone between shoulder and ear, an ergonomically incorrect practice that should be avoided. For those who want to talk with both hands free, there's a jack for an optional headset.

The handset has a slightly larger four-line display screen, allowing users to do almost anything that can be accomplished at the base station, including listening to answering-machine messages and storing a list of frequently called numbers.

What's most unusual about the Gigaset is the "intercom" feature. Any handset user can talk with any other handset user, and any handset can be paged from the base station for a conversation that doesn't require a phone line.

This obviously isn't important for families living in small apartments. But it's a wonderful way to keep in touch for those lucky enough to have big houses or to live in a rural area where the backyard extends beyond shouting distance.

And it's even more important for Siemens's target market of small-business owners. Employees throughout a store or a small manufacturing plant can have the benefit of a walkie-talkie and a telephone together in one device.

The handsets can also function as a room monitor, creating an audio link back to a speakerphone built into the base station. Users can even program the system to listen for a noise above a preset level -- a baby crying, for instance, instead of sleeping -- and ring the base station to provide an alert.

In the Gigaset instruction manual, Siemens provides a scenario showing how much can be accomplished simultaneously: "Handset 1 could be talking to Handset 2, while Handset 3 talks to a customer on external Line 1, the desk station talks to another customer on external Line 2 and Handset 4 checks the Answering System for messages."

Not that the Gigaset is perfect. The huge array of features -- I haven't even mentioned Caller ID, password protection and other functions -- is confusing to manage, and some common tasks, such as tying a handset into an outside call already under way at the base station, require several awkward steps.

But for anyone trying to pull together a group of people or manage a large volume of phone calls, either family or business, the Gigaset could be a worthwhile investment.

For those who don't require quite so much telephone horsepower, a slimmed-down Gigaset 2402 costs $269. This model offers one cordless handset and charger along with a plain base station that leaves out the built-in phone and answering system, but otherwise works in the same way with the cordless handsets.

At the Consumer Electronics Show last winter in Las Vegas, I saw several other companies exhibiting similar products, some of which used a personal computer as a base station.

This competition, I hope, will drive prices down and put a premium on easy-to-use design. That will hasten the day when cordless phones are ready to work out of the box as part of a smart system handling all our phone-related tasks.