Digital Content

The use of cell phones to track down criminals in the country is a fairly new system which has paid dividends. While many assume that cell phones are private, what they do not know is that they are the easiest way to trace the location of the user. One announces their location by the act of making a call, as the phone has already selected the strongest base station it can find -- which is probably the nearest one. So as long as you keep talking, the system can locate you to at least the nearest cell.

The size of a cell depends on many factors including the terrain and user population density. In busy areas, the carriers deploy many small cells to maximize the capacity of the system. In such an area, you might be located to an area as small as a few city blocks. It is not just the cell phone that is in use which can be tracked down. There is technology which can track an idle phone.

If cell phone users only placed calls and never received them, there would be no need to track their location even when idle. But a substantial number of calls are made to cellular phones.

That is where the phone announces itself to the system with a short message on the access channel so that the system knows exactly where to direct a page in case of an incoming call.

If the mobile moves to another cell, it re-registers in that new cell and the system updates its database accordingly. The mobile also re-registers occasionally even if it stays in the same cell, just to refresh the database entry.

Seated next to a radio, one will occasionally hear interruption on broadcast as the phone 'reports' to the base station. Most phones give no audible or visible sign that they are registering. The kidnapping of businessman Abdulkarim Popat by gangsters in May 1998 serves as a useful example.

Popat was kidnapped by three youngsters and driven to a hideout in Karen where he was held for several days. However, their attempt to use his phone led the police to their hideout where the trader was rescued and the gang leader shot dead.

More recently, a murder case in Eastleigh area of Nairobi was resolved when the court pieced up information from the cell phone of the deceased. To prevent a cell phone from registering and revealing your location is to turn it off. And to avoid doubt, remove the battery.

The Nation