3GPP is a multimedia file format that is primarily intended for storing audio and video files, as well as their transfer over 3G networks. This rather sophisticated technology was developed by the consortium Third (3rd) Generation Partnership Project, whose name gave the abbreviated name of this format (3GPP). The developer created this format so that the third generation of mobile phones can use smaller files. Another task is to unify the format of audio and video files for compatibility with various mobile devices. 3GPP files can be played not only on 3G phones, but also on 2G or 4G phones.
AMR is a sound file format with a specific focus. Created a long time ago, before the advent of MP3. some sources call the developer Ericsson. The name of the format is an abbreviation for Adaptive Multi Rate. Sound files of this format are intended for mobile devices and in GSM cellular networks. Using this format provides a small file size due to the technology of signal coding in the speech frequency range. Effectively compressing audio recordings of human speech makes this format often used in voice recorders on mobile phones, for voice recordings, and for MMS messages.