signal duration

A multifrequency (MF) or dual-tone multifrequency (DTMF) signal timing interval during which the signal is being transmitted. For MF signals the signal duration interval begins when the last tone of the MF tone pair exceeds 90% of its steady-state value and ends when either tone of the MF tone pair falls below 90% of its respective steady-state value. For DTMF signals the signal duration interval begins when either tone of the DTMF signal is within 1 dB of its eventual steady-state value and ends when either tone falls 1 dB below its steady-state value. [T1.414-1998]