I remember a thread a while back where someone was asking for a util
to play .GSM files.

I found this info at:
http://voip-info.org/wiki-Asterisk+sound+files

If you scroll 1/5th of the way down you will see some options for
Playing GSM files on Windows:
This can be done using freely available Quicktime player.
You can use this free Winamp plugin
http://www.mlkj.net/gsm/winamp_plugin_gsm_codec.php
Another useful tool is j2 messenger. 

I would think that the Quicktime way would work on Macs too, and even
the winamp plugin would be preferable to j2 messenger ;-)

- Ben
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist