Model RAD-1A from Viking Electronics is a ring-trip paging device that answers incoming phone calls and converts audio to a 600 Ohm output. This is the standard for most paging amplifiers today. The RAD-1A is compatible with phone line emulators such as, cellular-to-analog adapters, FXS ports on an ATA connecting to VoIP/SIP phone service, as well as CO lines and analog PABX extensions. When activated, the RAD-1A can trigger built-in relay contacts to activate the connected paging amplifiers. Using the optional RAD-1A security code can help prevent unauthorized access to your paging system.