On Feb. 18, Jay Sincavage will make one last phone call to say goodbye.

He'll bid farewell to the network technology that powered his first cell phone, an old StarTac — once considered the technologist's model of choice — that's bulkier than his wallet. At midnight that day, wireless networks nationwide will start shutting down the old analog networks that launched the cell phone business 25 years ago. Now, with the vast majority of the country's quarter-billion cell phone users calling and texting over digital networks, only about 1 million customers still use analog networks.

The Federal Communications Commission authorized carriers to phase out those networks to free more airwaves for digital services. So the nontech-savvy who haven't upgraded their phones in several years, as well as people in areas too remote to receive digital signals, could end up without a lifeline.

Sincavage, who lives in suburban Washington, plans to summon power to his StarTac and, with a few dozen other analog loyalists, make a final call with the obsolete technology.

"Maybe we'll overload the network and make it crash one last time, for old times' sake," Sincavage said.

The demise of a mainstream technology often happens under the radar, as companies and consumers embrace new formats. The record player and the tape recorder faded gradually. DVD rentals phased out VHS tapes. Now the CD appears to be making a slow exit, replaced by digital and downloadable music.

For the past seven years, mobile-phone companies have pushed people to upgrade their analog cell phones by offering discounts and rebates on new digital phones.

Each successive generation of the network was more efficient, sending more calls, pictures, videos and text messages over the airwaves. Maintaining the old networks became an expensive chore.

The cellular switch-off is the first phase of a larger transition to digital technology that will culminate next year with the end of analog television signals.

Other widely used technologies also rely on analog cellular networks. Older versions of OnStar, the communications system installed in many cars, will stop working next month. General Motors, which owns OnStar, said some cars made as recently as 2005 cannot be upgraded.

About 400,000 security systems use analog networks as backups to land lines, according to the Alarm Industry Communications Committee. In homes without land lines, the analog network is the only connection.

AT&T, Verizon Wireless and Alltel say less than 1 percent of their customers use analog services, which the companies plan to phase out over the next year. Sprint Nextel and T-Mobile already use all-digital networks, but their customers may be affected if they roam on other carriers' analog networks.

Over the past year, Verizon Wireless has been contacting thousands of customers using analog phones to offer them digital models.

Analog signals translate voice communications through a series of radio waves that require a lot of airwave capacity. Digital signals convert voice and data — e-mail, text messages, photos — into bits of data that can be compressed, allowing the information to travel quicker and requiring less capacity.

While digital signals are considered more reliable than their analog predecessors, they don't travel as far and may not reach sparsely populated areas, such as mountains and deserts.

Andrew Moreau, vice president of corporate communications for Alltel, which serves many rural areas, said analog towers will be replaced by digital ones before the service is shut off.