Playing GSM files in Windows XP

I’m developing an application that uses the Asterisk system as the primary PBX. One of the features of this application is the ability to listen to recorded GSM files in Internet Explorer.

Does anyone know how I can get the GSM files to play in Windows Media Player (WMP)?

As a corollary, If I can’t play GSM files in WMP, how can I change the file format that a voicemail system in Asterisk will use as the default format? Note that the recordings should be of good quality and the file size should remain small.


I have heard an application called wavepad works pretty well…