Patent US 4,409,439

A controllable, alternative annunciator for connection to a subscriber's telephone line 14 (the regular telephone ringer being turned off or disconnected) for providing subscriber-controllable annunciation. When not set for a specific function, the annunciator provides a group of chimes (36) in response to each incoming ring signal. The annunciator can be set to be silent under certain electronically, predetermined conditions. Specifically it provides the following controlled functions: (a) non-chiming for selected intervals (24), (b) chiming only after the first three ring signals (26L), (so that a secretary can answer a normally ringing extension before an executive hears any chime), (c) non-chiming after the first ring signal (26R) (to prevent repetitive ringing signals which might disturb a sleeper), (d) chiming only after a caller rings according to a predetermined code (28) (to prevent chiming from unwanted callers). The coded ringing (d) can either be allowance of chiming only after a caller rings for a predetermined relatively long period (by which time an uninformed caller would hang up), or (2) allowance of chiming if a caller rings twice, hangs up, and calls again within a predetermined period. The controlled functions are implemented by converting incoming ring signals to DC pulses (46B) and employing controlled chime oscillators, (40) timers, (42) counters, (42) and other interconnected logic and control circuitry (44-78) to process the pulses according to the desired function.