What is an ALAW file? An ALAW file is an audio file saved in the A-Law Compressed Sound (A-Law) format, which saves data compressed with the standard A-Law audio compression algorithm in the G.711 audio codec . It typically stores a recorded voice message delivered via telephone. ALAW files more commonly use the .al file extension ( .AL files).

More Information The Consultative Committee for International Telegraphy and Telephony (CCITT) originally developed the A-Law format. Then, the Telecommunication Standardization Sector of the International Telecommunication Union (ITU-T) superseded the CCITT and now maintains the format. The A-Law format is one of two versions of the G.711 audio codec. The other version is Mu-Law, also written as µ-Law. Most of the world, including Europe, uses the A-Law compression algorithm. However, North America and Japan use Mu-Law. Both compression algorithms are used in 8-bit pulse code modulation (PCM) digital communications. The A-Law and Mu-Law compression algorithms are similar. They offer 2:1 bit compression and optimize the dynamic range of an analog audio signal for digitization. However, they provide different coding levels and bit inversion, and A-Law compression provides less dynamic range, resulting in more minor distortion. For this reason, calls between two countries using the two formats default to A-Law compression.