[Kamailio-Users] call keepalived using rtimer?

[Daniel-Constantin Mierla]

On 02/18/2009 09:01 PM, Iñaki Baz Castillo wrote:
> El Miércoles, 18 de Febrero de 2009, Noel R. Morais escribió:
>   
>> I didn't understand the problem regarding CSeq...
>>     
>
> Well, read in RFC 3261 about CSeq and how it's used to order in-dialog 
> requests.
>   
... and the short version is that each party in a call keeps track of 
CSeq numbers from remote side. Newer request must have the CSeq higher 
that the previous one to be considered valid.

If you are proxy in the middle: [caller] ---- [proxy] ----- [callee]

when you send a new sip request to callee (just for example), then the 
callee will update the remote CSeq. When the caller sends a request, 
does not have any idea that the proxy sent intermediate requests and 
will use a CSeq number lower that what the callee expects, therefore 
callee will just drop it. In this way, the BYE might not be accepted.

But, as Inaki pointed, you should go over the SIP RFC, you will get it 
better from there and will help to configure properly kamailio sip server.

Cheers,
Daniel


>   
>> A lot of solutions use keepalives with INVITES ...
>>     
>
> But NEVER sent by a proxy. A keepalive can only be performed by an endpoint or 
> a B2BUA (an endpoint in fact).
>
>   

-- 
Daniel-Constantin Mierla
http://www.asipto.com