HOW TO TELL WHEN YOU ARE ROAMING

The boundaries that mark the end of one phone company's domain and the beginning of another's are invisible. Unless you've left your home area and entered another. But your phone can.

One of the indicators an a cellular phone is labeled ROAM. It serves several purposes. When you leave your home region and enter another, the ROAM indicator will light and stay lit as long as you are within range of a cell site. If you are on your way from one city to another, the ROAM indicator will go out and be replaced by the NO SERVICE light as you pass through an area in which cellular service is not yet available.

The ROAM indicator serves another purpose. All cellular phones are equipped to switch automatically between two services, wireline and nonwireline. The service you normally use is programmed in the phone's memory to give one priority over the other. This doesn't matter if there is only one cellular carrier in your region, but it's important if both a wireline and a nonwireline service are active. On many phones you can program which service is to have the priority over the other and even lock out one or the other completely. (The mechanism that does this is called an A-B switch. A services are the nonwireline services, B services, the wireline ones. All cellular phones have A-B switches, but some are more versatile than others.)

If you leave your A-B switch in automatic or priority mode as you travel, your phone's ROAM indicator, instead of lighting steadily, may begin to flash slowly. This tells you that the service your phone is "listening to" is a service other than the one it is programmed for- perhaps a wireline service when you normally use a nonwireline service. Usually, your phone will automatically make the switch over, and, except for the flashing light, there will be no difference apparent to you.

If you often ROAM to the same areas, there are phones available that hold multiple numbers. This way you will be "local" even when you are roaming away from home, and as a result, will not be billed as a roamer.

The flashing indicator can be startling the first time you notice it. Don't be alarmed, there's nothing wrong with your phone. It's just keeping you informed of what's going on.