SIP registration fails from one ER605 to another ER605 but works with Sonicwall with SonicOS

Installing and Using OpenWrt
1

I have a FusionPBX server on a public ip and on my work network, I have a sip phone (Fanvil X4U v2).

My FusionPBX server has openwrt setup with port forwarding to allow all traffic from the public IP of our work network to pass to the internal IP of the server.

For whatever reason, when I use the Sonicwall NSA 2400 registration works for the phone and calls can be made and received but when I swap it out for the ER605 with the same configuration, it will not register at all. I have NO LAN to WAN firewall or NAT rules.

Both ER605 have the most recent stable release and no addition modules/software other than what is in the base image.

SIP ALG is disabled on the Sonicwall.

Is there something I should be looking for in the ER605 to make it work?

2

I suggest to investigate the SIP traffic with sngrep or (more general) with tcpdump.

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3

All I see in wireshark is a REGISTER sip:pbx.xxxxxxx.tld

Our DNS server responds to the phone when the phone queries the fqdn.

If I had to guess, it looked like the outbound ports were being rewritten, hard to tell without seeing what is happening on the router. Is there a way to enable connection monitoring on the router?

4

You may need to install the kmod-nf-nathelper-extra package, but be aware of a potential risk.

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5

tcpdump is your friend.