So, any tips for when this happens …
An end-user has Comcast Xfiniti in their home-office.
They are using the ISP’s provided gateway as their router/firewall/WiFi.
They do not have their own router “behind” the ISP’s device.
They are a DHCP client (no static IP from the provider).
We can get their phone to register
(using Ethernet cable to the ISP equipment).
We can also get a softphone registered
(Windows 10 PC with headset)
But: both devices have 1-way audio …(they cannot hear the other side)
x101 Phone: Fanvil phone: Chan_SIP on PBX (5060/ UDP)
x102 Phone: Windows 10: PJSIP on PBX (5160 / UDP)
We’ve tried calling from other extensions to extensions …
We’ve tried calling into a DID directly to the phones …
They have 1-way audio on all calls (they cannot hear the other side).
Using sngrep to view the INVITE / RTP details:
We see the RTP address is a 10.0.0.x IP address
This is the local LAN IP address of the Comcast Xfiniti process
This is where the NAT woe is at …
The networking process from Comcast is not replacing the 10.0.0.0 IP address to the DHCP public IP address
I do not recall what this is called when it happens.
Using sngrep to view the REGISTRATION details:
We can see the outside Comcast DHCP public address
This is why the phones will register
No NAT woes on registration … Registration looks clean.
What we are thinking about to do next:
Comcast is telling us that their gateways do not have a SIP ALG setting and/or that it is already off/disabled
We were going put the Comcast Xfiniti gateway into “pass-through” and put a decent router with WiFi behind it.
We were going to try to build a TLS based extension and see if this works (2-way audio).
We are hearing that TLS extensions do not face NAT woes as much.
The SangomaOS firewall is disabled / stopped
All other phones (in the main office) register fine and have 2-way audio. They have been working daily for years now.
This is only happening for a remote user working from home.
Thank you for your thoughts and TIPS (esp) about using TLS.