It seems the default recording format for new numbers (voicemail and call recordings) was set to MP3 by mistake. It is now WAV for all new numbers.
The MP3 option is the lowest quality option, and not the smallest size, so we would suggest anyone using MP3 consider the options and change if they wish. We have added a new options as well.
The options are:-
WAV: This is the largest file, with 8KHz 8bit alaw mono (voicemail) or stereo (recording). It is the best quality and is directly the data from the telephone network.
ZIP: You can opt for the WAV file zipped (may save 40% of file size)
OGG: OGG/Vorbis is the best trade off for quality and size that we offer
MP3: Provides compatibility with many players and is a lot smaller than WAV, but not as good quality as OGG or WAV