R2 Signalling - Register Signalling

Register Signalling

R2 register signalling is a family of protocols that govern the conveyance of addressing information during the addressing phase and how the call attempt turned out during the disposition phase. Although in the 1960s R2 register signalling was represented by electromechanical devices that could generate multi-frequency audio tones and by electromechanical devices that could detect those audio tones, by the latter 1970s these electromechanical registers also could be represented by digitized PCM audio in DS0 channels of an E1 other than the R2 line signalling DS0 channel in that E1.