It is an ITU-T standard (Recommendation) for audio encoding, titled Pulse code modulation (PCM) of voice frequencies released for use in 1972.

Both are logarithmic, but A-law was specifically designed to be simpler for a computer to process[citation needed].

So for example, input decimal value −21 is represented in binary after bit inversion as 1000000010100, which maps to 00001010 (according to the first row of the table).

Note that no compressed code decodes to zero due to the addition of 0.5 (half of a quantization step).

This is to provide plenty of 0/1 transitions to facilitate the clock recovery process in the PCM receivers.

G.711.0, also known as G.711 LLC, utilizes lossless data compression to reduce the bandwidth usage by as much as 50 percent.

No internal method of identifying or separating the layers is defined, leaving it to the implementation to packetize or signal them.

[9][10] A decoder that doesn't understand any set of fidelity layers may ignore or drop non-core packets without affecting it, enabling graceful degradation across any G.711 (or original G.711.1) telephony system with no changes.

Like G.711.0, full G.711 backward compatibility is sacrificed for efficiency, though a G.711.0 aware node may still ignore or drop layer packets it doesn't understand.