NEW YORK CITY ? About 4.7 million Cingular Wireless subscribers with older phones will have to pay $5 extra each month as the company tries to prod them to get new handsets so it can devote its entire network to one type of signal.

The new surcharge, unique among the major U.S. carriers, will be added to bills starting in September, the company said Monday.

Cingular reported last month that roughly 92 percent of its 57.3 million customers use phones based on the globally dominant technology known as GSM, or Global System for Mobile.

The rest have handsets based on one of two older technologies. One dates back two decades to the first-generation of mobile phones, which used an “analog,” or non-digital, signal to transmit calls. The second is a digital transmission technique known as TDMA, which stands for Time Division Multiple Access.

Like other U.S. cellular carriers, Cingular is required by the Federal Communications Commission to keep providing analog service until early 2008 so long as it still has customers with those phones.