Conversion of 3pg files to mp3 file format

As far as we know, no 3PG multimedia format exists, so it is unlikely it is possible to convert 3pg to mp3 with some audio converter. It is very likely that you were looking for 3gp to mp3 conversion, which is export of 3GP multimedia file for wireless network to standard MP3 and this is doable with pretty much any multimedia converter.

Open 3PG file    Open MP3 file