[asterisk-users] Festival through AGI can't handle strings longer than 15 chars

[Mario]

I'm having a tough problem when using Festival with Asterisk through 
AGI: it seems that when I pass more than 15 chars to the Festival 
command, when from inside an AGI, no sounds (speech) at all is generated.

The following (from inside the dialplan) correctly works:

  exten => 333,1,Answer()
  exten => 333,2,FESTIVAL(Telefono spento uno)
  exten => 333,3,Hangup

But, when moved from within an AGI, the same Festival command doesn't work:

  EXEC FESTIVAL "Telefono spento uno"

the symptom is that no text is played, although the return code from 
command is zero.

One important note: if I shorten the text to "Telefono spento" (i.e. at 
most 15-chars wide) everything works as expected.

I really can't figure out the reason of this weird behavior. What I can 
do is to exclude some possible reasons:

1. It is not a festival-related problem since when called from the 
Dialplan everything works as expected.
2. It is not a language-related issue, since I tried this both with 
English and Italian
3. It is not a missing call to flush()... yes, I added a flush() at the 
end of my Python-based AGI call
4. It is not a problem related to Python, since I use Python extensively 
with AGI

Does anyone have a hint on what I can do to investigate or solve this 
problem? Does enyone know if this is a known bug?

Thanks in advance,

Mario