Abstract: A single-tone receiver for a device which only needs simple data which can be encoded in the seven or eight single tones which can be generated by an ordinary pushbutton telephone is provided. A telephone line interface circuit receives a signal from the telephone line. The input signal is not filtered to separate the high-frequency tones from the low-frequency tones prior to their detection. A zero crossing detector coupled to the telephone line interface detects zero crossings of a received single-tone input signal. A microprocessor coupled to the zero crossing detector counts the number of zero crossings in a period and compares the count to counts corresponding to each of the seven single-tone frequencies.

Abstract: A modular telephone housing 12 adapted for structurally and electrically coupling to other like modular telephone housings. The housing includes two tapered ribs 60 and 62 disposed at one end thereof, and two corresponding tapered grooves 104 and 106 disposed at an opposite end thereof for mating with the tapered ribs of an adjacent modular telephone housing. A male connector 18 includes a plate 34 coupling to one end of a flat cable 16, a resilient backing strip 44 between the plate and the contact strip, and two alignment pins 46 and 48. A female connector 20 includes a plate 74 coupled to the other end of the flat cable, and two alignment slots 82 and 84.