asterisk users - Jul 2005 - Exception flag set on 'UniCall/2-1', but no exception handler

Hi

When I make a call from the outside to asterisk and the call is asnwered, 
all is OK, but when I make a call from the outside to asterisk and hangup 
before the call is answered, you got this WARNING in the console:

Jul  6 19:33:08 WARNING[10037]: channel.c:1521 ast_read: Exception flag set
on 'UniCall/2-1', but no exception handler
Jul  6 19:33:08 WARNING[10037]: channel.c:1521 ast_read: Exception flag set
on 'UniCall/2-1', but no exception handler
.
.
.
Jul  6 19:33:08 WARNING[10037]: channel.c:1521 ast_read: Exception flag set
on 'UniCall/2-1', but no exception handler
Jul  6 19:33:08 WARNING[10037]: channel.c:1521 ast_read: Exception flag set
on 'UniCall/2-1', but no exception handler

and the warning has repeted and the extension ringing forever, until
you offhook the extension or stop de asterisk

Current configuration:
Connectet using E1 R2 to a Venezuelan telephone company
RedHat Linux 2.4.20-8 #1 Thu Mar 13 17:54:28 EST 2003 i686 i686 i386 
GNU/Linux
libpri, zaptel, asterisk CVS (07 Jul 2005)
spandsp 0.0.2
libsupertone, libunicall, libmfcr2 0.0.3

Any idea

Thanks
Jose chiantera

Ing. Jose Chiantera