Extension Cannot Call Out


Hello All,

I’m assuming firewall / internet issue on this one. I’m just looking for some confirmation.

I’ve got a system in Canada with an extension in France. This has been working for just about two years flawlessly.

The extension if France is connected to a dual wan firewall with a slow ADSL connection 2 Mbps symmetrical and a decent 4g connection 70 Mbps by 15 Mbps.

Recently, the dual wan firewall has failed, the customer has reconfigured the network to use the 4g connection only.

Since then, the customer cannot make phone calls over the desk phone only. They also have GS Wave on their cell phone. For trouble shooting, I’ve had them turn off the cellular data, using Wi-Fi only, and ensuring I’m seeing the 4g IP address when looking at the extension in the UCM (to ensure the customer got the cellular data disabled correctly)

The phone is registered.
I can call them with zero problems.
When they make calls, they get “No Response” on the phone.

This is what the capture from the phone looks like when placing a call.


Today, I factory reset the phone, installed the latest firmware and manually setup the minimum account info I needed to place a call. Thinking something in the config might have become corrupt. Same issue persists. I can call him successfully but he cannot call out.




Can’t tell as not enough info.You mention two phones, desk and WAVE. What phone is the capture related to? I question the observations about the WAVE as it the desk phone was indicated as “cannot make calls over the desk phone only”.

The green part appears to be the section of interest -

  1. In the INVITE look at the contact and connect headers and see if they are showing the public IP of the French 4g router.
  2. It appears to me, on the surface, to be a latency or NAT issue. There is no response to the challenge by the PBX or whatever it is connected to.
    Look at the times between each query and response and see if any are over 500ms.


Have you tried using another port? I know that some ISP blocks the port 5060. Maybe try in SIP-TLS on 5061?

Also, maybe try using TCP instead of UDP.