Many others keep their landline-phone service grudgingly, only because it is needed for things like fax machines. But even they often use their cellphones at home, because their friends and family members dial their cellphone number routinely, and their personal phone books are inside their cellphones.

But there is a big drawback to using a cellphone at home, especially in a large house: You have to schlep it around with you from room to room. By contrast, landline phone service can be used via either cordless or corded extension phones. Now, T-Mobile, one of the big U.S. cellphone companies, is rolling out a new system that it hopes will make cellphone service at home more convenient and even cheaper to use.

The service, being introduced this month in two test cities, Seattle and Dallas, allows you to use a cellphone account with any corded or cordless home phone, with multiple extensions, for just $10 a month. That very low price gets you unlimited domestic calls.

This new T-Mobile service, tentatively called Talk Forever Home Phone, is likely to be available nationally in a few months. It works via a special Wi-Fi wireless router that you must buy, with a two-year contract, for a one-time charge of $50. The router, which can either replace or supplement your existing wireless router, is essentially a stationary cellphone that marries an in-home Wi-Fi network to the T-Mobile cellphone network.

I have been testing the new system and found that it worked well, and it was extremely simple to set up and use. For my tests, I used a cordless phone supplied by T-Mobile, which included a base station and one extension handset. I was able to make and receive calls all over my home in exactly the same manner, and with exactly the same quality, as I do with my normal cordless landline service.

While T-Mobile is selling this cordless phone as a $60 option, it isn’t necessary for use with the new $10 service. The only new hardware that is required is the special Wi-Fi router.

However, there are some significant downsides to the new T-Mobile service that might make people think twice about dumping their landlines. For one thing, it doesn’t work with fax machines, home-security systems and other devices that rely on dial-up modems. Also, unlike landline phones, it doesn’t automatically transmit your home address to 911 emergency centers. You have to manually supply that address to T-Mobile during signup, and the company then sends it to your local emergency center.

Another downside: You must be a T-Mobile cellphone customer to buy and use this $10 monthly home service, and your T-Mobile plan must either be an individual plan costing at least $40 a month or a family plan costing at least $50 a month.

Finally, while you can transfer your current landline phone number to this new service, it cannot share your existing T-Mobile cellphone number. So people who are used to calling you on your cellphone will still do so, and you will still have to race for the cellphone or carry it around to receive those calls. You also can’t transfer your cellphone’s address book to the new home phone.

The special router is made by Linksys and looks very much like a typical Linksys router, except for the fact that it has two standard telephone jacks in the back and slots inside for T-Mobile SIM cards, the same kind that are inside a T-Mobile cellphone.

You can use the special router as a replacement for your current Wi-Fi router, but I just plugged it into an existing port on my old router, inserted the SIM card, and then plugged the cordless-phone base station into one of the phone jacks. It worked immediately, and didn’t affect or degrade my existing Internet service.

In addition to enabling the phone service around my house, the router was also usable by my computers for Internet connectivity, though it doesn’t support the new, fast “n” flavor of Wi-Fi.

This new system is not a so-called voice-over-Internet-protocol phone system, such as Vonage. It doesn’t carry your phone calls wholly over the Internet, but merely uses the Internet to get them to the T-Mobile cellphone network, which then carries the calls as if they had been made on a cellphone.

T-Mobile says the system will work fine even if you don’t have T-Mobile cellphone coverage at your house, because the call doesn’t rely on the cellphone network for its first leg and only is routed to the cell network once it reaches a T-Mobile switching center.

If you are a T-Mobile customer and can live with this system’s drawbacks, the $10 monthly fee may be hard to resist. But this new system is far from a perfect replacement for landline phones.

• Email me at mossberg@wsj.com. Find all my columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

Well, one of the American phone carriers, T-Mobile USA, has taken a step toward that ideal. It’s offering inexpensive phones that can make voice calls over either the company’s regular cell network or almost any Wi-Fi wireless network, including those inside your homes; open, password-free networks outside your home and T-Mobile’s system of 8,500 U.S. Wi-Fi hot spots in places like Starbucks shops.

These phones can switch seamlessly between Wi-Fi and T-Mobile’s regular cellphone network, even in the middle of a call, without dropping it, so you can just keep talking as you move in and out of Wi-Fi range. For instance, you can start a phone call at work over Wi-Fi, then get in a cab and the call will automatically switch to the T-Mobile cellular network. The process also works in reverse.

Even better, calls conducted over Wi-Fi, or calls that merely begin on Wi-Fi and then switch to the cellphone network in the middle, aren’t counted against your monthly allotment of minutes — no matter how long they use the cellphone network. (Alas, it works the other way as well. Calls begun on the cellphone network do consume minutes, even if they switch in the middle to Wi-Fi.)

Other cellphones have this built-in Wi-Fi, including Apple’s famed iPhone. But in these phones, the Wi-Fi is intended primarily for data use — Internet or email — not voice calls.

I’ve been testing T-Mobile’s new system, called HotSpot@Home, with a $50 Nokia 6086 flip phone and it works pretty well. I was able to start or finish calls at my home with my existing Wi-Fi setup and use an optional wireless router T-Mobile offers. The system also worked in several Starbucks in different cities, and in several commercial locations with open Wi-Fi service.

In general, my test calls switched seamlessly between the Wi-Fi and cellphone networks, and call quality was good. But in a couple of cases, the calls broke up or were dropped.

Of course, this cool new setup isn’t free. HotSpot@Home is an add-on feature to a regular T-Mobile calling plan. Through Sept. 25, it costs $10 a month for a single line and $20 for a family plan that covers up to five lines. If you sign up by then, you keep those introductory rates ever after. As of Sept. 26, the monthly fees increase to $20 for a solo line and $30 for the family plan. These are flat fees that don’t vary by how much calling you do.

There are downsides. The only phones available now, the Nokia and a Samsung, are very basic $50 ones with a two-year contract. However, T-Mobile expects to offer more phones. In a few weeks, it will sell a modified version of a sophisticated smart phone. The company refuses to identify the phone, but Web rumor sites suggest it’s a new version of the BlackBerry Curve with Wi-Fi built in.

Another downside: The first two phones don’t work with Wi-Fi networks that require log-in screens, other than T-Mobile’s. So, you can’t use other providers’ networks in hotels, airports and similar places. The phones lack decent Web browsers, and T-Mobile has automated access only to its own hot spots. Future smart phones with better Web browsers should overcome this limitation, but you might have to pay usage fees to the owners of non-T-Mobile networks.

Also, the phones don’t automatically connect to newly encountered Wi-Fi networks, so it takes time to go through the steps necessary to set up the new networks. They do automatically connect to networks used before that you’ve saved.

Also, making calls over Wi-Fi takes more battery life. Talk time on these first phones using the power-hungry technology is only two-thirds what it is on a regular cell network.

Finally, the flat-rate fee for unlimited Wi-Fi calls covers calls only to U.S. phones and doesn’t work from T-Mobile hot spots overseas.

Still, if you have lousy cellphone coverage at home or your office or tend to use a lot of monthly minutes, and you have access to Wi-Fi, the new HotSpot@Home could be a promising option.

Email me at mossberg@wsj.com. Find all my columns and videos online free at the new All Things Digital Web site, http://walt.allthingsd.com.

In fact, this category is getting so crowded that it’s hard to follow all of the contenders. T-Mobile and Sprint, for example, have just announced very similar smart phones running Microsoft’s latest Windows Mobile software. Both feature horizontal keyboards that slide out from beneath the screen. The T-Mobile Wing costs $299 after various rebates, while the Sprint Mogul, which runs on a faster network, costs $399.

But I’ve been testing two other new smart phones that I find especially interesting. One is the latest attempt by BlackBerry maker Research In Motion to appeal to consumers. The other is a high-resolution camera phone by Nokia, which costs more than even the iPhone.

The new BlackBerry Curve 8300, sold by AT&T, is sort of a cross between the maker’s low-end consumer-oriented Pearl and its larger, more traditional models like the 8800 series. It costs $199 after rebate, with a two-year contract.

Unlike the Pearl, which manages its slender size by sporting only a squished keyboard where two letters must share each key, the Curve has a full, if slightly compressed, keyboard. I found it no problem to use accurately. It does, however, use the Pearl-like trackball instead of the famous BlackBerry side-mounted wheel.

To accommodate the keyboard and a wider screen, the Curve is wider and a bit thicker than the Pearl, and has more of the traditional BlackBerry look. And it’s over 20% heavier. But it’s narrower, shorter and lighter than the 8800, though a bit thicker.

The silver-colored Curve doesn’t boast any technological breakthroughs. It’s mostly an attempt to bring the BlackBerry’s email capabilities to a model that doesn’t compromise the keyboard the way the Pearl did. It has all the traditional BlackBerry features, plus a two-megapixel camera, a slot for a memory card, and the ability to play music and videos.

In my tests, I had no trouble at all sending and receiving email on the Curve, taking or displaying pictures, or playing music. I was able to move over some songs and pictures from my own computer, and they displayed and played as promised. Voice quality was fine, and phone talk time is about four hours — reasonable but not outstanding.

In a welcome move, the Curve has a standard headphone jack, capable of playing music in stereo and handling phone calls. It also includes Bluetooth for wireless headsets and use in cars, but it doesn’t have Wi-Fi wireless networking. It also runs on AT&T’s relatively slow EDGE network instead of the carrier’s faster data network. And the Web browser is mediocre.

The Nokia N95 lacks a full keyboard, physical or virtual and its email is primitive, but that’s not its main purpose. This device is the best combination of a camera and a phone I’ve ever tested, and includes a long list of other media features.

The camera boasts five megapixel resolution, highly unusual for a phone, and it takes marvelous photos. When I transferred my shots to my computer, they were large, sharp and vivid, just as if they’d come from a standard camera. The camera has Carl Zeiss optics, autofocus, multiple flash settings and various scene settings. It also has a burst mode capable of taking six shots in rapid sequence.

But getting such a good camera in a phone will set you back a whopping $749. And you can’t buy it through any phone carrier, only from Nokia’s Web site (nseries.com) or from various electronics stores. You have to buy a phone plan separately.

Nokia’s N95, left, and BlackBerry’s Curve 8300

Like the Curve, the N95 has good voice quality, but runs on the slow EDGE network, though a future version could support faster networks. Unlike the BlackBerry, the current N95 also can use Wi-Fi networks. Battery life is only fair: 3.5 hours of talk time. While Nokia touts the phone’s Web browser, I found it to be unimpressive. But the phone includes GPS mapping, with optional navigation. It also accepts memory cards for storage.

Physically, the N95 is small, but chunky; on one side, it looks like a plum-colored camera. If you slide its screen in one direction, the keypad is revealed. Sliding it the opposite way reveals standard controls for playing music and video clips. I was able to move pictures and songs from my computer, but the songs failed to display album covers when played.

For $749, you could buy the Curve and a very nice digital camera. But the N95 is for photo enthusiasts who want an all-in-one device. The Curve is a more mainstream smart phone that aims for a balance of features at a low price.

• Email me at mossberg@wsj.com. Find all my columns and videos online free at the new All Things Digital Web site, http://walt.allthingsd.com.

A slew of new services using voice-recognition technology aim to eliminate the hassle of checking voice messages on wireless devices. These services transcribe recorded messages into text, which then is sent as email to email-equipped devices such as personal digital assistants and BlackBerrys, or as a short text message to phones that don’t have the email function. If in doubt about transcripts’ accuracy, you can always click on the attached audio files or dial in to hear the original voice mail.

To see how efficient these services are at transcription, I tested two voice-recognition applications: one from start-up SimulScribe, based in New York, and another from Atlanta-based SpinVox, a subsidiary of SpinVox Ltd. of the U.K.

Overall, both services work pretty well and are easy to use. I was able to read transcribed texts in a fraction of the time I would have spent dialing in to hear them. I was also able to sift through my messages and go directly to the ones I wanted to check, as opposed to having to listen to every single one sequentially. And the transcripts end the hassle of having to jot down names, numbers or addresses.

Another advantage is that the transcribed messages are sent immediately after the voice mails. When I was on a train and passing in and out of reception areas, I got my written messages faster than if I had tried voice mail only. Users can forward the messages to others or reply by calling back, sending an email or text messaging.

Signing up with SimulScribe.com took just minutes. After setting up an online account naming a cellphone carrier, I got a confirmation email with instructions on how to activate the service on my phone. SimulScribe, launched this past September, costs $9.95 a month for 40 transcribed messages plus 25 cents for each additional message. The service is compatible with all wireless carriers.

Currently, SimulScribe transcribes English voice mails only. A voice mail left on my phone in Spanish wasn’t transcribed at all. The company says it’s testing a Spanish system to add to the service in a couple of weeks.

Activating SpinVox’s Spin-my-Vmail on the phone was easy, too. After signing up on spinvox.com, the company sends subscribers a guide to using the service on the phone. I was able to activate “call forwarding busy/no answer” to divert messages to my SpinVox voice mail just by changing a setting in my T-Mobile’s cellphone settings menu.

I received an email in my mailbox whenever someone left me a voice mail. Each had the number of the caller, the transcript, date and time the message was received, plus a message code I could type into the keypad after accessing my voice mail to hear the original audio.

U.S. customers can get a free one-year trial by sending an email to gamma@spinvox.com, during which time the company expects to launch the service in the U.S. first through Cincinnati Bell and later through other carriers. Bloggers can also test Spin-my-Blog, which lets users speak a posting to their blogs from any phone. Sign-up for that is also at spinvox.com.

SpinVox, first launched in the U.K. in May 2005, transcribes in English, French, Spanish and German. Unlike SimulScribe, messages left to me in Spanish were successfully transcribed.

One friend who left me a voice mail on both services said she was pleased to be reminded by SimulScribe that her message would be transcribed so she should speak slowly and clearly.

Users of SimulScribe get unlimited inbox storage so they don’t have to delete old mail. Both services work better with hand-held email devices such as Treos or BlackBerrys than with the cellphones that don’t have the email capability. The number of characters that can be transcribed into SMS text is limited.

With SimulScribe, long messages delivered by SMS are parsed over multiple text messages. The same happens when customers use SpinVox on CDMA cellphones. Customers using SpinVox on GSM phones like those from Cingular or T-Mobile fit three-minute calls on one text.

Sometimes, the transcriptions contain misspellings, missing words or unnecessary punctuation marks. A friend left me a voice mail on my cellphone with SpinVox’s Spin-my-Vmail service. She ended it by asking me if I was sick of Thai food, but the transcribed note, amusingly, turned it into: “Hi Sarmad, it’s Kain(?). I’m calling at 4:09(?). I just wanted to see what the plans were for tonight. Are you interest in dinner, are you up for Lasagna(?).”

Words — mostly names — spelled phonetically, some numbers and undecipherable words are usually followed by a question mark.

Aside from sporadic imprecision, I liked SimulScribe more, mostly because it eliminates the need to dial in any passwords to get a voice version of transcribed messages. But it’s hard to beat the free trial of SpinVox and its multiple-language transcription capability. Both services are a nice addition to hand-held devices if you can overlook a few nuisances.

• Email me at sarmad.ali@wsj.com. Walt Mossberg is on vacation.