[SIP Beyond VoIP] STUN keep-alive

Mihai Richard mihai.richard at softvision.ro
Mon Jan 16 11:44:38 CET 2012


I forgot to say that I am using sipsimple 0.19 on the client side and the
server is OpenSIPS.
Both clients are indeed behind the same NAT router, but problems appear only
after one of them has a long period of inactivity(no messages sent to the
server). If one client has a long period of inactivity, it cannot be
contacted by other client but in turn it can contact clients that recently
had activity.

--
Mihai

On 1/16/12 12:14 PM, "Andreas Sikkema" <asikkema at unet.nl> wrote:

> Mihai
> 
>> I am having some problems with starting an audio call between two clients if
>> they registered at some time one from another(aprox. 1 minute). I used ngrep
>> to see sip traffic and this is what I saw: if clients register at aprox. the
>> same time(less then a minute apart) if one of them sends the INVITE message
>> the other client receives it, however if they¹ve registered at some time one
>> from another, the first client to have registered does not receive the
>> INVITE.
> 
> Are these clients behind the same NAT router? I have seen lots of
> consumer/prosumer grade NAT implementations that can't handle two SIP
> clients on LAN side using the same local port (say 5060) when talking
> to the same server on the WAN side. The last one to talk to the server
> will receive all the traffic from the server, regardless of which was
> the intended receipient. Moving one of the clients to a different
> local port from which to send the messages resolves this. There is
> nothing the server can do, the problem is on the LAN side of the NAT
> router.




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