asterisk users - Oct 2005 - Festival() works fine when I call from PSTN and not when I call from XLite... What's going on?

Hello there,

For some reason, Festival() works fine when I call from PSTN (via an IAX 
connection that I've got from Voice Pulse), but does not produce any 
sound when I call from my X-Lite SIP phone.  However, if I use text2wave 
instead of Festival(), both my PSTN and my X-Lite connections seem to 
work fine.  Does anyone know what is going on?

Note that the Festival server is being called in both cases without any 
noticeable problems.

Thanks in advance for any lead,

Leo