3GP (3GPP file format) is a multimedia container format defined by the Third Generation Partnership Project (3GPP) for 3G UMTS multimedia services. It is used. Jan 10, 2017 A 3GP file is a 3GPP Multimedia file. Learn how to open a 3GP file or convert a 3GP file to MP3, MP4, WMV, MOV, or some other file format. 3GP is an audio and video container format that is generally used in 3G cell phones. But it can also work in 2G and 4G cell phones. This MP4 based container.