[SR-Users] Dispatcher and "src based" routing algorithm

[Olli Attila]

Hello,

I am using kamailio 4.4.3 (x86_64/linux) 5a2195 and Dispatcher module to 
route calls towards PSTN (4 pstn gateways). The Dispatcher module is 
using round robin mechanism to select the pstn gateway.

I have built a routing logic in a way that when call arrives to Kamailio 
from one of the PSTN gateways, and fails to route towards an external 
sip target, the call is marked as CFU call (a diverting call) and routed 
back to PSTN with different B number, but the actual challenge is that I 
would like the target PSTN gateway _not_ to be the same PSTN gw from 
where the call originally came in to Kamailio. This feature is requested 
because of the technical limitations of the pstn gateway software.

So is there any mechanism in Dispatcher or elsewhere in Kamailio to do 
this?

Basically I would need a flag or something to mark the pstn gateway when 
the call comes in and assure that when routing back to pstn, the same 
gateway would not be used at all, or it should be used as last target 
from the four gateways in Dispatcher.

Cheers,

-- Olli