Storage Requirements for Voice Mail Messages

By default, Asterisk records each voice mail message in two different files:

1. a file with GSM encoded voice - 96 KB/min (this file is usually sent by e-mail to the user)
2. a file with 16 bit PCM encoded voice - 940 KB/min (this file is played when the user checks the voice mail inbox)

Therefore, the total required space for one minute of voice mail is about 1 MB. This translates in theory to:

500 GB = 500,000 minutes

For practical purposes, when you take into account several GB required by the system itself and a bit of margin, you can record approximately 8,250 hours in 500 GB.

Alternately, it is possible to change the Asterisk default settings and record only one of the files, thereby increasing your storage capacity tenfold. In this case you need to ensure that a suitable application, which supports the GSM codec, is available to play the files.