When used with an analog phone line, the VR-1A will provide "ring" indication, "on the phone" indication and "message waiting" indication for both "stutter dial tone" and standard message waiting voltage. In this application the VR-1A connects directly to tip and ring. When used with a headset, you can end those nagging interruptions that occur when associates' don't realize you are on the phone because you are using a headset. The VR-1A will flash twice indicating to everyone that you are on the phone and you are not to be disturbed. The VR-1A installs in the handset/headset jack using an included "T" adapter. When used with electronic or digital phones, the VR-1A won't have you guessing which phone is ringing in busy offices. The flashing LED can be seen up to 100 feet away. The VR-1A connects directly to the electronic phone’s speaker. Applications Call centers Telemarketing Product support groups Office cubicles C.O. based voice messaging Purchasing departments Sales offices Features Displays "ringing," "on-the-phone" or "message waiting" LED visible up to 100 ft Power supply included Compact package mounts with double-back tape Connects with modular cord Special "T" adapter provided for handset applications One year warranty Made in the USA Specifications Power: 120V AC/12V DC 500mA UL listed adapter provided Dimensions: 70mm x 50mm x 40mm (2.9" x 2.1" x 1.5") Shipping Weight: 1lb. Environmental: 0°C to 32°C (32°F to 90°F) with 5% to 95% non-condensing humidity Connections: (1) RJ14 jack Light: 19mm (.75") red LED Visibility: 30m (100') typical Message Waiting Voltage: 90V - 125V