Patent GB-191311590-A (GB)
Title: Graded Service Automatic or Semi-automatic Telephone System.
Inventor: BARON HAROLD
IPC: H04M1/677
Filed: 1913-05-19
Granted: 1914-05-19
Abstract: 11,590. Baron, H., [Heimann, G.]. May 19. [Addition to 11,261/12.] Automatic and semi - automatic exchange apparatus; impulse-transmitters.-In order to exclude a calling subscriber from access to certain ranges of numbers, for the purpose of providing a graded-service system as described in the parent Specification, the impulse - transmitter is constructed so that, if an interdicted number is called, the impulse-dispatching contact is short-circuited or open-circuited throughout the stage corresponding to one of the digits, so that the call is not completed. In view of the possibility that the subscriber might avoid the restriction by repeating the ineffectual digit, a device may be provided for preventing the operation of the transmitter for more than the normal number of digits. The transmitter may be rendered operative for numbers within the interdicted range by means of a coin or by the operation of a meter. The invention is described as applied to a transmitter of the type in which a numbered finger - dial is operated repeatedly to send the successive digits. Auxiliary switches 1, 2, 3, 4, Fig. 1, are set by the movements of the dial to terminals corresponding to tne called number, and a switch 5 is moved to successive terminals as successive digits are transmitted. If all numbers in the range 6000-6999 are to be interdicted, the sixth terminal of the switch 1 would be wired to the first terminal of the switch 5, and in any attempt to call a number in the interdicted range the impulse-dispatching springs 6 would be short-circuited, during the stage corresponding to the despatch of the first digit, by a circuit through the switches 1, 5. To prevent the calling of a number in the range 6300-6399, the sixth terminal of the switch 1 would be wired to the switch 2, and the third terminal of the switch 2 would be wired to the second terminal of the switch 5, so that if the first two digits of the called number should be 6 and 3, respectively, a short-circuit would be closed through the switches 1, 2, 5. By an extension of the same method it is possible to render even a single number inaccessible. The short-circuiting paths may be opened, as indicated by the contact 7, by means of a coin or by a meter - operating device, and different short-circuiting paths may be controlled by coins of different value. Constructionally the switches 1, 2, 3, 4 consist of rotatable disks 13, each having a stud 26 for operating fixed pairs of springs 27, 28, and an equivalent for the switch 5 is provided by groups of springs 25, 24, 31, Fig. 2, there being a separate group for each disk 13 and the spring 24 being moved from the spring 31 to the spring 25 when the corresponding disk leaves its normal position. At the first rotation of the finger-dial 10, the first disk 13 is carried round by an arm 21, which is hinged on a slider 19 and engages with the shoulder 22 of a slot in the disk. As the dial 10 returns, the disk 13 is held, against the restoring-action of a spring 14, by a detent 16, and the engagement of a roller 29 with a curved wing 30 on the first disk 13 forces the slider 19 to the right along a bar 18 so that the arm 21 passes through the slot in the first disk and engages the shoulder 22 of the second disk. The next rotation of the dial 10 therefore operates the second disk 13, and so on. When the telephone is replaced on the switchhook the detents 16 are tripped, so that the springs 14 restore the disks 13 to their normal position, and the slider 19 is moved back to the left by the spring 20, the arm 21 passing through the slots in the disks 13. In the modification shown in Fig. 5, the short-circuiting contact 44 is controlled by a lever 45, which has a cross-bar 48 engaging with a series of notched disks 46<I> &c. corresponding to the different digits. In semi-automatic systems, subscribers entitled to a certain grade of service may be grouped in connexion with an operator having an impulsetransmitter of the kind described above, the arrangement being such that when the transmitter is set for an interdicted number a signal lamp is lit, warning the operator that a metering-key must be operated in order that the connexion may be established.