[asterisk-users] 3 locations 3 vpns

[freebsd at tango.lu]

Hello,

I have the following setup:

Network A <==> Network B <==> Network C
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   \----------------------------------------/

All 3 locations are connected with a layer2 vpn to make it transparent 
with the same ip range 10.0.0.x/24.

Network A and C is close to each other and have another direct routed 
tunnel 192.168.1.x/24.

I would like to route the calls between A and C on this direct tunnel.
What is the best way of accomplishing it?

The phones are older OpenStage models and only support 1 SIP server, 
that would have been my first idea just to setup a secondary Asterisk on 
location A or C and have the phones register on both sip servers.

My other idea would be to setup a secondary Asterisk on location A or C 
and link the two with IAX. However B is strategically more important 
than A or C since it has the dialout setup to PSTN. Let's say the second 
asterisk is setup at C and that loses connectivity with B (while A still 
have it's tunnel up), that will result both A and C are separated from B 
also in this case all of A's phone traffic is routed through C.

Any ideas are welcome.