With Converter App, you can convert 3GPP files into many other formats:
3GPP to MP4 | 3GPP to M4A | 3GPP to WAV | 3GPP to MOV | 3GPP to MKV | 3GPP to WEBM | 3GPP to AVI | 3GPP to FLAC
→ All 3GPP Converters
If you want to keep working with your final MP3, try:
MP3 to TXT | MP3 to DOCX | MP3 to PDF | MP3 to SRT | MP3 to MP4 | MP3 to WAV | MP3 to AAC | MP3 to OGG
→ All MP3 Converters