One of the questions we often get here at Scanner Master is how I can listen to whatever is around me. While the ZIP Code scanners are the way to go for this some people think that by using the Close Call feature one can listen to all the activity in the area. While this would be a great idea it really doesn’t work that way.
Close Call and ZIP Code scanning have some similarities but are really two different animals. Close Call (and the similar Whistler/GRE/RS feature called Spectrum Sweeper or Signal Search) is a near-field receiving option that scours the bands for strong signals and locks in on them. You can then see the frequency displayed. This is great but it has limitations.
The range Close Call works at depends on the strength of the signal, it has to be very strong to trigger. Portable radios usually have to be within a few hundred feet, mobile radios within a block and base stations or repeaters within a few blocks. Sometimes you can get stations further away but that depends on so many factors like antenna, frequency, elevation etc. that anything beyond those distances is considered luck.
Close Call is a great way to find new frequencies, especially at less documented sites like shopping malls and events. It is a great tool to find all those walkie-talkies used at locales and events but cannot be used as a replacement for proper scanner programming. One feature it lacks is the ability to look up a channel in the database or programming of the radio.
ZIP Code programming is recommended for those traveling thru an area if you don’t know what frequencies are being used there. Chances are the main channels are already documented on Radio Reference and thus should be in the internal database on your ZIP Code enabled radio. Uniden ZIP Code scanners also support the use of a GPS to automatically update the location as you move.
Be sure to use the right location service for your needs. Need to find new local (VERY local) channels? Use Close Call. Need to listen to specific services or systems in a particular area? Use the ZIP Code feature.