It (
Voice Interoperability Plan for Emergency Responders (VIPER) Trunking System, Various, North Carolina - Scanner Frequencies) is a state-wide radio system (similar to those in various other states) where state, county, and local agencies share a common system. It allows a way for the various agencies to communicate as they might using seperate systems, but also allows an easy switch to common channels during emergencies where multiple agencies need to communicate. In theory, at least, there may be a cost savings since the expensive infrastructure is shared by many agencies and radios or equipment can be purchased in larger quantities resulting on larger discounts.
A few things you need to remember when you're programming a scanner for the system:
* Program in only the site(s) that are nearby (if you travel, "nearby" might include those you travel through as well). Generally, you only need to use the one or two closest sites since the signals for those far away won't be picked up anyway. If you have sites programmed in that are out of range, you may want to lock them out to speed up your scanning.
* You'll only hear transmissions for talkgroups that are "affiliated" with the site you're currently monitoring. If someone in that site's coverage area is on a talkgroup you'll hear them, if not you won't.
* If a transmission is encrypted, you may hear digital noise, silence, or it may keep scanning (which one depends on how your scanner handles encrypted transmissions).
