Automatic telephone subscriber's appts. for through-dialling PBX - has third switches clearing first marking switches given time after first selection

摘要

The automatic telephone subscirbers' appts. is for through dialling p.b.x.s. First switches store the first selection or engagement of the subscriber's appts. Second switches are activated either by the first selection or engagement such that the subscriber set is marked as engaged if selected a second time. Third switches clear the first selection or engagement such that the subscriber set is marked as engaged if selected a second time. Third switches clear the first switches a given time after first selection and reset them to their initial state. The secon switches are located in a test circuit to permit testing. The test circuit is opened after the first clearing operation has occurred. All the switches may be in the subscriber's appts. or located centrally.