[Asterisk-Users] switch in extensions.conf

[Daniel Salama]

Can anyone provide more information on switch or point me to where I  
can find more about it?

The only I've been able to find on the wiki is:
http://www.voip-info.org/tiki-index.php?page=Asterisk+-+dual+servers

and towards the bottom of (section Forwarding to another Asterisk):
http://www.voip-info.org/wiki-Asterisk+config+extensions.conf

Some of the questions I have are:
1) If I have an asterisk machine being used only as a VoIP gateway to  
the PSTN, and I have multiple asterisk machines behind it waiting to  
make or receive calls through/from the gateway, can I have multiple  
switch statements in the same context, so that if the gateway tries  
to contact asterisk machine 1 and it's not available, try the next  
one and so on?
2) How to configure the other asterisk machines to use the VoIP  
gateway for all outbound calls? I read somewhere that you cannot have  
circular references using switch, but I'm not sure if it refers to  
what I'd like to do
3) Assuming the VoIP gateway cannot contact any of the other asterisk  
machines, can the voip gateway put calls on hold and continue trying  
and only disconnect or play busy tone after some pre-defined period  
of time?

Thanks,
Daniel