The StarLink SLE-LTEV-CFB-PS is a Commercial/Residential Fire and Burglary Radio by Napco. It comes mounted in a red metal housing with a SLE-ULPS-R power supply and 16.5V/20VA transformer. It can function as a backup to existing telephone lines, or as sole path primary communicator. In backup mode it will automatically switch the communication channel from the telephone line to the network when telephone line trouble is detected. The SLE-LTEV-CFB-PS is Verizon Network Certified.