SER and Asterisk - Loadbalancing

I have a question for anyone out there with information regarding load balancing inbound calls using SER.

What I am looking to do is have a ‘farm’ of 10 asterisk servers which will process inbound IVR calls. I want to set up a single device which my provider will send the initial INVITE request to. I want that device to basically just forward the INVITE request to one of my 10 asterisk servers. After the invite is forwarded i simply want the initial device to step out of the SIP and Media path. It would look something like this

GATEWAY —> INVITE —> Load Balancer —> INVITE --> Asterisk Server

while the response would look like (load balancer out of path)

Asterisk Server —> TRYING —> GATEWAY

I am currently acheiving this goal using a Foundry ServerIron 4G which provides SIP loadbalancing, but I want to make the switch to something i have more control over.

Does it sound like SER or OpenSER is a good fit for this?


Yes, I believe any of the sip proxy’s you mentioned would work. They don’t need to be in the media path if you have public IP’s.

Here is a link to the OpenSIPS documentation on the dispatcher module (It even has an example config). … tcher.html

Thanks for the reply. I have public IP space, so I shouldn’t have any problem taking the OpenSIPS device out of the media stream.

Moving along to my next question… is there a mechanism in SIP to take the server which forwarded the initial INVITE out of the route? For example, I would like my asterisk server to finish the transaction directly with the gateway, instead of having to route everything through the OpenSIPS server. Would look something like this

Gateway --> INVITE --> OpenSIPS --> INVITE --> Asterisk
Asterisk --> OK --> Gateway
Gateway --> BYE --> Asterisk

(obviously that transaction is simplified greatly, but you get the point)