the 0 dBm0 periodic sequence as given in Table 2, in either mu-law or A-law as appropriate, is applied to the decoder at the digital reference point, a 1 kHz, 0.775 volt rms sine-wave signal appears at the decoder output. 0 dBm0 is 3.14 (A-law) or 3.17 (mu-law) dB below digital full scale." A more commonly used unit for digital signal levels is dB Full Scale or dBFS. The relationship between dBm0 and dBFS is unfortunately ambiguous. It depends how you define rms and peak levels in a sampled system. The level of 0 dBm0 is defined as specific pattern in a sampled system (see standards referenced below). However, In an A-law coded system, the maximum level of a sinusoidal in such a system is +3.14 dBm0. The ambiguity is if the level is a peak or rms value. Today, the interpretation by many companies tend to go towards the rms interpretation. This means that +3.14 dBm0 = 0dBFS peak and -3dBFS rms. This also means that the same signal has a peak level of +6.14dBm0 peak. This means that the commonly used Point of Interconnect level of -16dBm0 can be transformed to -22.14dBFS rms in a A-law codec system. (-22.17 dBFS rms in a μ-law codec system). References Sources ETSI G.711 Radio frequency propagation