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). Self-adaptive tone learn apparatus (50) and programs (88) are provided to learn the particular signature characteristics of call progress tones transmitted by the telephone switching system (14).