Iptables breaks a working VoIP phone?

Kenneth Burgener kenneth at mail1.ttak.org
Sat Nov 10 15:07:05 MST 2007

Kenneth Burgener wrote:
> Hello.
> I made a switch in my firewall device, and now my Broadvoice VoIP
> connection is having some issues.

Just wanted to do a quick follow up on this issue.  I was able to
resolve the issue, after some discussion on the shorewall lists.  The
cause of the problem happened to be the iptables modules ip_nat_sip and

I assume the purpose of the modules are to help a dump sip device work
with NAT.  The problem is, I assume again, that Broadvoice had
configured the Sipura ATA device to work with NAT out of the box, so the
two were conflicting.

After disabling the modules, my phone now works wonderfully.  No port
forwarding necessary at all.

Thanks all who gave suggestions and ideas.

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