Conventional radio calls from clearing up to 8-10 kilometers, generally up to 3-5 kilometers, in situations where there are tall buildings or mountains block, call a relatively short distance.

When has the support of network intercom call distance of a few tens of kilometers. Network is to use the repeater (also called base stations or rotary table), automatically receive signals from radio transmitter, and carries on the enlargement and forward. Networking can enlarge the coverage of radio communication, extended range, clearing up to 10 to 20 kilometers (portable intercom) or 30 to 50 km (car radio), building covering basements, underground parking lot, severe fire channel such as shielding, usually called blind Angle.