3G2 is an audio / video format that was developed using the 3rd Generation Partnership Project 2 (3GPP2). The file extension is an improved version of the 3GP format. Today it is already outdated, despite the fact that it was previously updated. As a result of the implementation of the 3rd Generation Partnership Project, standards were developed that relate to methods of transmitting a wide variety of media data. For example, on mobile networks. The development of such standards, in particular, has led to the introduction of the 3G2 format and to the use of various types of media data on the global network for online streaming. This type of file is most often used on mobile phones, as well as on phones that support 3G. 3G2 video files can also be played on many computers. We emphasize that in this case there may be a need for additional applications. The 3G2 format is very similar to the MPEG-4 Part 14 series (MP4) format. However, in comparison with it, the 3G2 format is not so complicated. When you apply this type of file, you need to consider the possibility of reducing the requirements for the width of both the information transfer channel and disk space. So, the format for mobile phones is exactly what you need. 3G2 files have been specifically developed for phones operating in the CDMA standard.
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.