In order to listen to prerecorded gsm
messages in the Voice Prompt Manager
section of PBX Manager
(or any other Asterisk GUI) you need to have a gsm player software
installed. Most audio players are unable to work with these VoIP type gsm
audio files, however. Don´t even try the Microsoft GSM Audio Codec supplied with windows XP - it won´t work either.
If you are looking for a small, non-intrusive freeware program for playing gsm audio files in Windows, try out WavePad
You need to associate gsm file types with WavePad in order to have a one-click playback in the Voice Prompt Manager. This can be done within WavePad by selecting the gsm checkbox in Tools / Wavepad Options.