Loss of recording every 2min with SNOM phone

[Michael37]

Hello,

Many of our customers encounter disconnection / reconnection all day long on their SNOM phone.

After much research and testing, I found that the "keep alive" setting was now 60 seconds for the LAN.

On the configuration of a SNOM phone, I disabled keep alive by removing the 60 seconds and I no longer have the problem.

We believe the issues have happened since the last 3CX update.

Installation:
3CX Server (172.16.1.20/24) -> Fortigate Datacenter -> VPN IPSEC -> Fortigate site client -> Téléphone SNOM (192.168.100.10/24)

Provisioning is done in local LAN by entering the ip address of the 3CX server

We have been operating like this for several years and have had no problems except for a few weeks ...

We have hundreds of phones in this case ...

Could you help me please ?

I thank you in advance.

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- 3CX Version : 16.0.8.9
- Server OS : Debian 9 (Previously Windows Server 2012, same issue)
- Is the 3CX Server Hosted and where? The server is hosted in our datacenter, the interconnection between the datancenter and the customer is done by an IPSEC VPN link between two fortigates.
- IP Phone Make/Model/Firmware
- Provisioning Method: Local / VPN
- Has the Firewall Checker passed: YES
- Are custom Phone Templates being used: NO
---------------------------

 

[NickD_3CX]

Hi Michael,

Yes this change was introduced in the last template update, but we have not noticed such an issue as you describe it.

In the title you mention "Loss of recording every 2min" but in the text you say "customers encounter disconnection / reconnection".
Could you please help me better understand what exactly is happening?

 

[Michael37]

Hi,

The phones display every two minutes: "not registered", then "provisioning" or "registered"

For a few seconds the phone is no longer registered

 

[NickD_3CX]

I am suspecting that for some reason your IPSEC is blocking the STUN requests (those that happen every 60s) and when the phones are not receiving a response, they go unregistered until the next registration cycle.
I'd like to confirm that though.

Please start a PCAP through the snom phone interface and let it run for 3-4 minutes without making any calls, just so that we can check the registration cycle.
Then stop and save the capture, upload it to a GDrive or some other file sharing service and send me the link in a PM.

 

[Michael37]

I just sent you the pcap in PM

 

[NickD_3CX]

Thanks!

I had a look and it's most what I suspected I believe, there are no responses to the CLASSIC-STUN requests the phone is sending:


It should look something like this instead:


Can you check why there are no responses coming back to the phone?