AS NEW TECHNOLOGIES for telephones are harnessed, the lines between telephones and other digital devices, such as cameras and computers, are blurring.

Other new telephones are adding radio-like walkie-talkie capabilities. The Internet also is becoming a factor as companies begin offering Internet-based telephone services that are less expensive than traditional phone service.

Here's a look at some of the products and services behind these trends.

Walkie-talkie cell phones

Until the middle of 2003, if you wanted a cell phone with walkie-talkie capability, Nextel Communications was the sole supplier. But during the last half of 2003, both Verizon and Sprint rolled out walkie-talkie services. Additional wireless providers are likely to join the bandwagon in 2004.

Why all the excitement about cell phones that act like two-way radios? The main attractions of walkie-talkie calling are immediacy and the ability to talk to several people simultaneously. Businesses, which are the primary customers, also like the shorter communications that result from using a walkie-talkie.

Nextel Communications pioneered this technology, which allows users with enabled cell phones to push a button and talk directly to others on the walkie-talkie's call list. Like walkie-talkie radios of old, only one person can talk at a time. Nextel calls its service Direct Connect. Sprint's walkie-talkie program is called PCS Ready Link, and Verizon's service is Push-to-Talk. Although the industry is working toward a standard, walkie-talkie calls can't be made from one network to another.

As the three services vie for customers, the time it takes to make an initial walkie-talkie connection has become a competitive point, given the perception that customers like the immediacy of a walkie-talkie call compared with typical cell phone connection times. In Nextel's case, the connection is made in less than a second anywhere on its national network, which the company claims it built from the ground up with walkie-talkie communications in mind. Sprint has an initial connection time of three to four seconds. But transmissions are nearly instantaneous after that, it says. Verizon did not disclose typical initial connection time but says communication is nearly instantaneous once the initial connection has been made.

Sprint and Verizon walkie-talkie services are available in more areas than Nextel's because of their broader wireless networks. However Nextel, which has focused on offering services to businesses, plans to increase coverage in rural areas. It recently announced a cooperative venture with Extend America, which is expanding services in North Dakota, South Dakota, Nebraska and several western states.

Pricing of walkie-talkie service varies, depending on the supplier and the plan you choose, but the cost of a one-to-one walkie-talkie call is generally less than that of a cell phone call.

All of Nextel's phones are walkie-talkie enabled, including the new ruggedized Motorola i530. Sprint offers three walkie-talkie phones, including a ruggedized model, the Sanyo RL2000, and a new Sanyo video phone. In addition to digital service, all of its phones offer analog roaming. Verizon offers a single walkie-talkie-enabled phone, the Motorola V60p.

For information about walkie-talkie services, including coverage areas, contact the companies at www.nextel.com, www1.sprintpcs.com or www.verizon.com.

All-in-one phone, camera and personal digital assistant (PDA)

Smart phones, which combine cellular telephone capabilities with computer-enabled features, such as e-mail, have come a long way in the past two or three years. Witness the Treo 600 smart phone, from PalmOne.

The Treo 600, introduced by Handspring before the company was purchased by Palm, has attracted attention as one of the best multifunctional cell phones on the market since being introduced late last year. Although other smart phones have similar features, the Treo 600 has gained a reputation for handling each of its functions well.

The phone's broad feature set, including a Qwerty keyboard, is reflected in the price — about $500 with a service package. But if you are in the market for a PDA and a GPS-enabled cell phone with e-mail and Web browsing capability, it is worth considering. It is available from AT&T Wireless, Cingular, Sprint and, soon, T-Mobile.

Despite its multifunctionality, the Treo 600 is relatively small, 2.4 × 4.4 in. and just under an inch thick. It weighs about 6 oz. and looks like a full-sized stick-form cell phone. Most of the Treo 600's functions are controlled with a five-way rocker switch with a center button that allows you to switch from phone, e-mail, the browser, MP3 and video players.

The phone's PDA uses the Palm OS, which has a mid-range, 144-megahertz processor with 32 megabytes of memory. A stand-alone Palm OS PDA with similar specs would sell for more than $300. The backlit LCD is 2.5 in. square.

If e-mail is your thing, the Treo 600 handles up to five e-mail accounts and allows you to send text messages up to 160 characters in length. Its Web browser reformats Web pages in a single column, so you don't have to scroll right or left.

For more information, visit www.palmOne.com/us.

Internet-based telephones

Internet data lines have carried voice communications for years, but using the Internet to make a telephone call has been more complicated than picking up a telephone receiver and dialing. No longer.

Today, anyone with a high-speed Internet connection can make and receive Internet-based calls using a standard telephone plugged into a device that converts the analog signal (your voice) into digital data that travel to the recipient via the Internet. The person receiving the call picks up the telephone to answer as usual, and may not be the wiser unless you tell him. Likewise, the technology is seamless for incoming calls, whether or not they emanate from a traditional or Internet phone.

Consumer interest in Internet-based telephony — known as Voice over Internet Protocol, or VoIP — has taken off as kinks in the technology have been worked out. Growing awareness that VoIP is less expensive than traditional phone lines also has been pivotal. For example, Vonage, one of the technology's pioneers, offers an Internet phone line, plus unlimited local and long distance calls in the U.S. and Canada, for about $35/month. That's just a little more than the cost of a phone line in many areas. The package includes a free analog-to-digital converter box, plus a long list of free extras, including voice mail, call waiting, caller ID, call forwarding and three-way calling. In many cases, customers can keep their current phone number, too. Additional lines go for $4.99/month.

What's the catch? First, you must have high-speed Internet service, either via DSL, cable, fixed wireless (services such as Prairie I-Net) or satellite. In the case of satellite, delays inherent in the technology may be noticeable when you talk, though Internet phone providers say improvements in their technology compensate for this. Second, not all area codes are currently available, although this is changing rapidly. If your area code isn't available, you can choose a telephone number from another area code, but that means local calls to your phone will be long distance, though outgoing calls will be free with unlimited long distance calling. Also, be aware that if your Internet service goes down, or if there is a power failure, you lose phone service. Because of this, many Internet phone customers keep a traditional phone line as a backup.

If you think Internet-based calling is a flash in the pan, think again. Major telecommunications companies such as AT&T, Qwest Communications and Time Warner Cable have recently announced plans to offer the service, joining smaller players such as Vonage (www.vonage.com), Net2Phone (www.net2phone.com), VoicePulse (www.voicepulse.com) and 8X8 (www.8x8.com). Whether or not you buy Internet-based phone service, you may end up using it anyway. Industry analysts say that in the future telephone companies will rely heavily on the Internet for routing calls because Internet lines are cheaper than traditional lines and switches.