You can use any connection in VoIP, if you have a very low bandwidth you can use either G729 or G723 in codecs, in same cases you could try to use Opus it's not as widely available as it should be but it can solve your internet speed issues
You can use any connection in VoIP, if you have a very low bandwidth you can use either G729 or G723 in codecs, in same cases you could try to use Opus it's not as widely available as it should be but it can solve your internet speed issues