Abstract: Apparatus for recognizing a telephone call supervision signal by comparing its frequency and cadence to the frequency and cadence of a previously learned call supervision signal is provided as part of call completion equipment (10). Call progress tone detector (50) receives a call supervision signal and responds by outputting frequency parametric signals which indicate whether predetermined standard frequencies are present in the received signal. Microprocessor (74) determines the cadence of the received call supervision signal and outputs a corresonding cadence parametric signal. If it is beneficial to learn the received call supervision signal, the frequency and cadence parameters are stored in memory (78). Recognition circuits can then recognize a subsequent telephone call supervision signal by comparing its frequency and cadence parameters to the frequency and cadence parameters stored in memory (78) for at least one learned signal.

Abstract: Call completion equipment (10) is disclosed for use with a switching system (14) for assisting callers to complete telephone calls thereto. If a primary destination telephone set (16) is busy or does not answer, a message is transmitted from a message storage unit (54) to the calling party. The message relates to the selection by the caller of secondary destinations including a switchboard attendent 18, an alternate destination telephone set, a camp-on option or voice messaging facilities. A processor complex (72) processes the digits dialed by the caller in response to the message, using various look-up tables (85-87), and transfers corresponding information to the switching system (14). The switching system (14) completes the call to the secondary destination according to the information. The invention (10) provides automatic camp-on features (87) with regard to predefined telephone sets of the switching system (14).