[SR-Users] Calling users on another kamailio server

Brian Wallen bwallen at gmail.com
Mon Sep 16 14:27:00 CEST 2013

On Mon, Sep 16, 2013 at 7:34 AM, Daniel-Constantin Mierla <miconda at gmail.com
> wrote:

> Hello,
> On 9/12/13 10:08 PM, Brian Wallen wrote:
>> I currently have two independent kamailio servers. I'd like to set them
>> up in a way that user1 on server1 can make a call to user2 on server2.
>> After searching I've come up with two ways that this might be able to be
>> done. Can someone please sanity check these or point me in the right
>> direction?
>> 1. Have one registrar server and convert the other server to a proxy
>> 2. Keep them both as registrars and somehow make them each aware of the
>> users on the other server
>> I like 2 better because if one server went down users on the other server
>> would still be up. The only thing is I don't know how to set the servers up
>> to communicate with each other.
> the nat can create problems when a server is down - if the nat is
> symmetric, only the server that received the registrar can send back calls
> to the phone.
> Communication between users on two servers is as simple as using
> t_relay_to("proto:serverip:**port") after you do lookup("location") and
> no record is found.

Suppose I have three or more kamailio servers. If a call comes in and
lookup() returns that no record was found, how do I know which server to
forward to? Is that a case in which I should replicate the database?

> You have to add an extra check for the case the call was coming from the
> other server, not to forward back to it in case of no found again.

Thanks for the tip, I hadn't thought of that.

> Also, you should skip user authentication for calls from the other server
> (not do authenticate twice). Another aspect to take care is chaining
> rtpproxy, you have to use the flat for trusting the other server (r, iirc).
> You can also replicate the registration, but again, it can add troubles to
> the nat. Look at t_replicate() (in tm module).
> Cheers,
> Daniel
> --
> Daniel-Constantin Mierla - http://www.asipto.com
> http://twitter.com/#!/miconda - http://www.linkedin.com/in/**miconda<http://www.linkedin.com/in/miconda>
> Kamailio Advanced Trainings - Berlin, Oct 21-24; Miami, Nov 11-13, 2013
>   - more details about Kamailio trainings at http://www.asipto.com -
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