Abstract: A filter-type pulse counter system which separates pulses of desired frequencies from pulses of undesired frequencies, filters out the pulses of undesired frequencies, and then accepts and counts only those pulses of the desired frequencies.

Abstract: A system for screening out undesired signals from desired signals, the system being selectively programmed to effect this screening through programmed codes, the system also having means to utilize the desired signals to effect the performance of a selected function such as the sounding of a signalling means to indicate the transmission of the desired signals, the activation or deactivation of electrically controlled devices, or the actuation of a reprogramming means, the system being especially adapted to utilization in a telephone system for screening out undesirable calls and permitting desirable calls to effect activation of the selected functions.

Abstract: A system for selectively deactivating a telephone bell on a telephone instrument whereby when a telephone number is called, an auxiliary system automatically cuts in to prevent ringing of the bell until a predetermined code is dialed or touch-toned, at which time the telephone bell is actuated.

Abstract: A system for selectively deactivating a telephone bell on a telephone instrument whereby when a telephone number is called, an auxiliary system automatically cuts in to prevent ringing of the bell until a predetermined code is initiated by the calling station, at which time the telephone bell is actuated.