The BLK-4 provides high visibility indication of analog line status through a high powered LED strobe and / or beacon visual indicator. The BLK-4 is the ideal solution for the hearing impaired and can be used equally well in loud warehouses or factories, where ringing phones cannot be heard. Alternatively, the BLK-4 can be used to add emergency notification to pre-existing emergency phones by turning on the strobe light when the emergency phone is in use.

The included control module has a disable input which is ideal for two-button emergency phones, such as Viking's E-1600-20A, allowing "Info" button calls to be placed without activating the relay (turning on the emergency strobe light, camera, etc.).

Four DIP switches are provided for turning ring detection on or off, off-hook / loop detection on or off, 12VDC or dry relay contact output, and for selecting a ring cadence mode which allows the relay to follow ringing or to remain activated during the off time of standard ring cadence. The control module can be installed on any standard telephone line or analog PABX / KSU station. The strobe can be interfaced to flash on ringing, off-hook or a combination of ringing and off-hook (line in-use).

For outdoor installations where the unit is exposed to precipitation or condensation, use model BLK-4-EWP. For more information on Enhanced Weather Protection (EWP), see DOD 859.

The BLK-4 includes: (1) control module, (1) SL-2 blue LED strobe light, (1) 12VDC power adapter, (16) gel-filled butt connectors and (1) single gang weatherproof mounting box with gaskets and hardware.