SIP Server with dynamic public IP address and dyndns

Question

Is it possible to run SIP server with dynamic public IP address and dyndns?

The question is what happens when IP address is changed and DNS is not yet updated.

Answer 1

Yes it is. The problem's exactly like running a web server or any other kind of server on a dynamic IP address and dyndns.

If you're running a SIP User Agent and you advertise your SIP URIs with your dyndns name - say, sip:you@your.dyndns.domain.com - then for the time from when your IP changes until the dns update occurs, inbound calls won't reach you.

(Of course if you only advertise your URI with your IP address, you avoid the problem, but other people will only have a transient URI for you.)

If you can register with a SIP proxy running on some static IP address, your User Agent could check for the IP address change and update its registration. That would drastically reduce the interval during which calls won't reach your agent.

Answer 2

I don't know what a SIP server does exactly, but I'd say it's basically possible, but there would be outages if the IP changes, during which time the server would be unreachable. You'd need to set a very tight interval to updating the current IP in your DynDNS client.