Snom D785 Phones temporary unregistered

[Stefan D.]

We have 3CX v16.0.9 Enterprise Perpetual, on Windows server 2019.It is hosted on premises in a ESXi 7 environment.


We have Snom D785 FW 10.1.73.16 and through the day we see that the phone become unregistered. We are using the 3CX provided template for the phones, nothing customized. They are all local in their own VLAN with the PBX appliance.

Looking at the phone logs we see this:

Sep 15 07:47:28.316 [NOTICE] SIP: process auth: Match challenge for user=MR728nGueG, realm=3CXPhoneSystem

Sep 15 07:47:28.395 [NOTICE] SIP: Subscription_refresh delay: rnd_delay: 1, delay: 0

Sep 15 07:48:28.380 [NOTICE] SIP: process auth: Match challenge for user=MR728nGueG, realm=3CXPhoneSystem

Sep 15 07:49:22.923 [NOTICE] PHN: Login failed 3 times, blocked for a minute!

Sep 15 07:49:26.076 [NOTICE] PHN: TPL: Socket 52 idle/connect timeout

Sep 15 07:49:26.076 [NOTICE] PHN: TPL: Socket 48 idle/connect timeout

Sep 15 07:49:26.077 [NOTICE] PHN: TPL: Socket 47 idle/connect timeout

Sep 15 07:49:26.091 [NOTICE] PHN: TPL: Socket 49 idle/connect timeout

Sep 15 07:49:26.091 [NOTICE] PHN: TPL: Socket 50 idle/connect timeout

Sep 15 07:49:26.148 [NOTICE] PHN: TPL: Socket 51 idle/connect timeout

Sep 15 07:49:28.509 [NOTICE] SIP: process auth: Match challenge for user=MR728nGueG, realm=3CXPhoneSystem

Sep 15 07:49:39.447 [NOTICE] PHN: TPL: Socket 53 idle/connect timeout

Sep 15 07:50:28.676 [NOTICE] SIP: process auth: Match challenge for user=MR728nGueG, realm=3CXPhoneSystem

Sep 15 07:51:28.906 [NOTICE] SIP: process auth: Match challenge for user=MR728nGueG, realm=3CXPhoneSystem


Is there anything that can be done to stop the disconnect and blocking? These are logs from the phone, and I don't see anything in the 3CX logs regarding the phone being blocked.

 

[JohnS_3CX]

Hi Stefan, better start from here so we can understand what type of installation you have:
https://www.3cx.com/community/threads/information-to-provide-when-requesting-help.67558/

 

[Stefan D.]

Hi Stefan, better start from here so we can understand what type of installation you have:
https://www.3cx.com/community/threads/information-to-provide-when-requesting-help.67558/

added the required info to the original post.

 

[JohnS_3CX]

Ok, so to begin with the "Login failed 3 times, blocked for a minute!" message you see in the phone is part of the firmware's exponential back-off strategy. It's a method that SIP devices use to avoid getting blocked by the remote server, so they "block" themselves for a short while from trying to connect again so that the SIP server will not consider the attempts as spamming or hacking attempts. 3CX also uses a similar strategy on its trunks, when they fail to connect.

Unfortunately that message does not tell you why the attempts failed (ie. it got no reply vs got a negative reply) but the fact that it is followed by "socket idle connect / timeout" implies basically that the phone did not receive any traffic back..

This could be practically anything.. From a bad cable, to a bad network connection, to firewall restrictions, to ISP restrictions (and not limited to just these factors of course).

What can you do, how can you troubleshoot this?

1. You can run a capture in the background, mirroring the phone's port and the PBX port
2. You can then filter for one specific phone, and analyze the captures
3. Look at the REGISTER attempts sent from the phone, and compare it with the PBX capture. Did the REGISTER reach the PBX?
4. If it did not then you know you are facing networking issues - investigate your network.
5. If it did reach the PBX then you look to see if a reply was sent back to the phone or not
6. Assuming a reply was sent, you then need to check the phone capture again and see if the reply arrived
7. If no reply was sent then we need to investigate the PBX

Obviously timestamps will be critical here, and will reveal time-slide issues so if everything looks ok, you need to scrutinize the time and make sure what the PBX capture has, will match what the phone capture has.

Sorry for the long post, this is not a straightforward issue to solve!

 

[Stefan D.]

Thanks for the time shift suggestion John. The PBX was about 5 minutes behind. i corrected the ESXi host NTP server and hopefully that will be the end of the issue

 

[JohnS_3CX]

Yep that should do it. Keep an eye for a few days and see how it goes!