[asterisk-users] Load balancing Asterisk.

[Grey Man]

> 3. Incoming calls - I admit complete ignorance. I don't know
> how OpenSIPS handles incoming calls, but for those to arrive
> at the user reliably they must arrive from the same IP address
> the user is registered to. Otherwise their broadband router's
> NAT firewall will just block the connection. How does OpenSIPS
> handle this? (does it handle this??)

That's the big question!

My company uses a custom SIP Proxy and SIP Registrar so I can't speak
for the details of SER derivatives but the theory is most likely the
same.

Our SIP Registrar records the proxy the REGISTER request arrived on
and updates the Asterisk realtime database outboundproxy field with
that value. When Asterisk needs to send an incoming call to the user
it looks up the SIP username in the realtime database and sends the
call thorugh the correct Proxy which solves the NAT issue you mention.

One trick for young players here is that the outboundproxyport setting
is broken in Asterisk so your Proxy will have to run on port 5060.

Regards,

Greyman.