TELEPHONES; TELEPHONE APPARATUS-NAMELY, PUSH-BUTTON TELEPHONE DIALS, TELEPHONE STATION SETS COMPRISING VARIOUS COMBINATIONS OF THE FOLLOWING FRATURES; 2 LINE GROUPS, DIRECT IN LINE, TIE LINE, MANAGER/SECRETARY EXTENSION, PUSH-BUTTON DIALING, SHORT CODE DIALING, LAST NUMBER REDIAL, CALL INTERCEPT, BROADCAST CALLS, AUTOMATIC CALL-BACK, MESSAGING, CONFERENCE CALLS, CLOCK DISPLAY, SECRETARY INTERCEPT/DO NOT DISTURB, AMPLIFIED RECEIVER, CANCEL KEY FOR ALL OF THESE FACILITIES, RINGING SOUND QUALITY, RINGING LEVEL, LOUD SPEAKER VOLUME, CALL PARK, CALL FORWARDING, VISUAL DISPLAY OF ONE OR MORE OF THE FOLLOWING; EXCHANGE LINE CALLS, EXCHANGE LINE OCCUPANCY, CALL WAITING MORE THAN 30 SECONDS, NUMBER OF CALLING EXTENSION NUMBER AND STATUS OF CALLED EXTENSION, NUMBER BEING DIALED, CALL DURATION, OPERATOR POSITION ACTIVATED, EXTENSION CONNECTED TO SECRETARY FACILITY, LINE STATUS, CALL WAITING, PERMANENT LINE, BUSY, FREE; KEY FOR CONVERTING ANY EXTENSION TO AN OPERATOR POSITION; ON HOOK DIALING, OR MUTE KEY; TELEPHONE COMBINED SET-NAMELY, TELEPHONE HAND SET WITH A MICROPHONE; TELEPHONE SWITCHBOARDS; COMPUTER TERMINALS; TELEPHONE TEST AND MEASURING APPARATUS, AND STRUCTURAL PARTS FOR ALL OF THE AFORESAID