asterisk users - Feb 2005 - international calls and NOANSWER

Hello,

I'm doing lot of international calls via Sixtel and VoipJet. And there are
some calls
which do not go through - Asterisk immediatelly returns with NOANSWER. And it is
not
because the dialed party does not pickup the phone, it is because the call does
not go
through the provider.

I've written a dial macro which route the call via second provider if the
first returns
CHANUNAVAIL, but I don't know how to handle NOANSWER when it is actually
CHANUNAVAIL...

Any ideas?

Thanks,
David