Intercommunication system with dial selected ringing

Claim 1

AN INTERCOMMUNICATING TELEPHONE SYSTEM COMPRISING A PLURALITY OF MASTER STATIONS EACH INCLUDING A RESPECTIVE TELEPHONE SET HAVING DIAL PULSE GENERATING MEANS; SWITCH MEANS FOR SELECTIVELY ALIGNING THE SYSTEM FOR INTERCOMMUNICATION BETWEEN LOCAL STATIONS, FOR INTERCOMMUNICATION BETWEEN LOCAL STATIONS ONLY, OR FOR NORMAL CONNECTION THROUGH A CENTRAL OFFICE OR FOR INTERCOMMUNICATION BETWEEN LOCAL STATIONS WHILE LINES TO THE CENTRAL OFFICE ARE MAINTAINED IN A HOLD CONDITION; FIRST COMMON MEANS RESPONSIVE TO THE DIALING OF A SINGLE DIGIT FROM ONE OF SAID DIAL PULSE GENERATING MEANS FOR SIGNALING A PRESELECTED ONE OF SAID STATIONS; SAID COMMON MEANS INCLUDING A TWOLEVEL STEPPING SWITCH HAVING CONTACTS CORRESPONDING TO SAID MASTER STATIONS ON ONE OF SAID LEVELS, A TRANSISTOR OSCILLATOR FOR GENERATING A STATION ALERTING SIGNAL, MEANS OPERATIVE ONLY AFTER THE TERMINATION OF THE GENERATION OF A SET OF DIAL PULSES CORRESPONDING TO A SINGLE DIALED DIGIT FOR INITIATING THE OPERATION OF SAID OSCILLATOR, MEANS INCLUDING, SAID STEPPING SWITCH FOR APPLYING A SIGNAL FROM SAID OSCILLATOR TO THAT ONE OF SAID STATIONS CORRESPONDING TO THE DIGIT DIALED THEREBY TO GENERATE AN AUDIBLE ALERTING SIGNAL AT SAID LAST NAMED STATION; A PLURALITY OF SLAVE STATIONS, AND SECOND COMMON MEANS INCLUDING SAID STEPPING SWITCH RESPONSIVE TO THE DIALING OF A SINGLE DIGIT FROM ONE OF SAID DIAL PULSE GENERATING MEANS FOR COMPLETING A CONNECTION BETWEEN ONE OF SAID MASTER STATIONS AND A PRESELECTED ONE OF SAID SLAVE STATIONS, SAID STEPPING SWITCH HAVING CONTACTS ON THE OTHER ONE OF SAID LEVELS CORRESPONDING TO SAID MASTER STATION.