Resources Contact Us Home
Telephone intercommunication system providing common access to a communication line

Image Number 4 for United States Patent #3931479.

A private telephone intercommunication system including facilities for connecting the system to a telephone central office. Common supervisory means are provided to control access to a line from each station.

  Recently Added Patents
Scalable architecture for rank order filtering
Superconducting magnetizer
Transfer of digital data through an isolation
Apparatus, method and program for image receipt, processing, conversion, and delivery to and from a plurality of external apparatuses
Music composition automation including song structure
Method for computing an energy efficient route
Cycloalkylamine substituted isoquinoline derivatives
  Randomly Featured Patents
Self-checking circuit in microwave equipment
Dynamically changeable virtual mapping scheme
Bicyclic heterocycles, drugs containing said compounds, use thereof, and method for production thereof
Primary galvanic cell
Method of fabricating component having internal teeth and rolling machine thereof
Pressure sensitive copying paper
Cable with a sheath made of steel, and a method and apparatus for forming the cable
Brake holding system
Solid state imaging device having signal noise combining circuitry for masking image reproduction errors
Lighting devices and methods of installing light engine housings and/or trim elements in lighting device housings