Sudden falls on UCM and VoIP Trunk


Hello, everyone,
at a customer I have a problem of sudden drops on Trunk VoIP on UCM with 4 phones GXP1830 The problem occurs at random on all phones. So the customer is in an external conversation and sometimes suddenly the conversation falls out, for no apparent reason.
The only element I currently have is the attached screen, as being a problem that occurs very rarely is difficult for me to leave “Network Troubleshooting” listening.
I understand that it could be everything, but my tests to date have been:
1 - reverse the phones between them by also changing the data network point
2 - restart router, firewall and UCM and the same phones
3 - I have a doubt about the Zyxel GS-1900-24HP POE Switch (not supplied by me and anyway I want to try to replace it next time)
4 - the data connection is on the Draytek Router and at the level of stability does not show any problems.

If someone had ideas and advice on what to try to do, I would be happy.


Take a look at the cdr for the two calls that dropped and see if there is any similarity in how long the call lasted.


unfortunately no, I would have liked to see the classic conversation that falls after 32 seconds, but no.
The same phones have 10/15 minute conversations, that’s why I’m surprised, and I ask you if you have any ideas.


I forgot, sometimes the conversation falls but there is no trace in the error log, unpleasant situation.


The two calls you show seem to be external to internal, does it ever fail from internal to external? Can you setup a SFTP server and do a continuous WireShark?


I do not find where to set the data to set SFTP, by chance they are the same as
Maintenasce/Backup/Datasync ?


Yes, enable the datasync as yu have indicated and then set the function to record to SFTP in the capture page.


ok thank you, nothing arrived and I didn’t understand why, then I realized that the pcap file arrives after pressing “stop”.


if using sftp, it should constantly load files on the server. I had to run one site for nearly two months straight.


Is something wrong?


you need to enable data sync and tell it the account details.


then, I try to explain myself, if I activate “Enable data sync” in the Backup/Data Sync page it forces me to choose one of the 4 options on “Choose Data Sync Files” that I don’t really care about, I just need the pcap file. For that it is disabled.
As you can see in the screens the pcap file in SFTP works, but it doesn’t send it in real time, it sends it only when I press “stop” Network Troubleshooting.
However, even if I activate what you say, it sends me it only when I press “stop” Network Troubleshooting.
I don’t think these settings are done very well, they are a bit confusing.


So, have it sync the fax files. There is a test button on the data sync page. In order for the function to work, it must pass this test.

You leave the capture running and send to SFTP. The system will continuously download 4-5MB files to the server that is assigned in the datasync page with the location and credentials.


yes, in fact, every 4.5 mb he sends the file, and it works, he did not send it in real time and I did not understand.
It works :slight_smile:


Well, now the key is to get someone to tell you exactly when it happened and what numbers. Then you get to go hunt it down.


Exactly, but as you know the customer (in general) is always very vague in the information


Let me know if you find any answers to this.

I have two customers with similar intermittent issues. I have not found the cause but it started after 1.0.18.x firmware on the UCM and I can’t prove anything…


It happens, but that can be external reason. Mobile switch station and fail etc.
Both info suggest drop from ITSP side, with normal clearing (hang up).


@lpneblett check if NAT on the trunk you have enabled it.


why do I need to check?