WHAT IS GSM?
GSM (Global System for Mobile) is an audio file format created for internet telephony in Europe. The GSM format is used to store recordings of telephone conversations. We’ve provided the specifications below for the GSM file type and a list of programs that can play GSM files.
European Telecommunications Standards Institute
A GSM file is encoded with a lossy CBR (constant bitrate) codec. Typically, the quality of the audio in a GSM file is 13 Kbps. Still, this bitrate is good enough for voice recordings. We’ve listed some of the programs that support the playback of GSM files below. Refer to this list if you’re not sure how to open this type of audio file.