[asterisk-users] Asterisk and failover

[Alex Lake]

I'm trying to implement a dual Asterisk Box setup where our carrier will 
be delivering SIP traffic to one of 2 units.

The idea is that to have a high uptime by handling traffic on box A 
while box B is being upgraded, then box B takes over the traffic, 
allowing box A to be upgraded.

The question is how can we drive Asterisk to make this happen? I need 
some primitives like "stop accepting calls" and "start accepting calls". 
One way (I guess) is to have a dial plan that just responds to any 
INVITE with a 3xx message and switch that in with a file rename and a 
console reload operation. Another way would involve the use of the 
OPTIONS feature of SIP, but I can't see where this is configured.

Any ideas or experience on this matter?

Alex