Communication system between local area network stations

A modem which comprises:

• an interface means adapted for connecting said modem to a computer;
• a central processor connected to said interface providing that said central processor is interfaceable with said computer;
• a memory means communicating with said central processor;
• a data processor adapted to communicate with a speaker and a microphone;
• a current generator adapted to provide line current to said data processor;
• a telephone communicating with said data processor;
• a data access arrangement adapted for connection to a central telephone office;
• a switch means for directing current to said data processor which in one position directs current from said current generator to said telephone and in another position directs current from said central telephone office through said data access arrangement to said telephone;
• a capacitor having one terminal connected to a terminal of said switch connected to said data processor and another terminal connected to a terminal of said switch connected to said data access arrangement circuit.

A method for communication between a first station and a second station, wherein said first and second stations are any stations of a local area network connected to a central office, said method comprising the steps:

• (i) dialing from said first station a telephone number, N;
• (ii) examining N and when N is for a remote party, then:
• said first station is connected to draw current from the central office and transmit signal directly to the central office and when N is a call number of a second station, then said first station is disconnected from said central office thereby interrupting line current from central office to station A, interrupting the dial tone;
• connecting a first current generator to supply current from the current generator to a data processing unit of said first station;
• sending signal N from said first station to said second station by capacitive coupling between the data processors of said first and second stations;
• picking up a telephone at said second station in response to a signal received at said second station;
• connecting said second station to said central office when said signal is from a remote caller and interrupting line current to said second station from the central office if said signal is a signal is from said first station;
• connecting a second current generator to a data processor of said second station providing that communication between said first station and said second station can take place without dial tone.