A dial pulse restorer for receiving and restoring telephone dial pulses which may be distorted, and also for discriminating telephone-hang-up pulses which may be applied to a telephone line when a remote telephone coupled to the telephone line hangs up. A particular use for such a dial pulse restorer...http://www.google.fr/patents/US4319091?utm_source=gb-gplus-shareBrevet US4319091 - Dial pulse restorer
