Hi We are having connectivity issues with 4 of our sites connecting by 3CX border controller back to the server this morning, It appears to be since 4am that the SBC lost connection to the 3CX server. The SBC log shows the following error ERR | 20170626-042755.827 | 3CXTunnel | TUNL | 5872 | TunnelTcp.cpp:262 | Bridge [3CXSBC15.0.61335] failure 'TLS handshake failed: error:00000001:lib(0):func(0):reason(1) + (err): error:00000001:lib(0):func(0):reason(1)' on TCP connection: secure negotiation Restarting the 3CX server or Session broker has not fixed this issue. Has anyone else seen this issue? Update... I have heard back from my 3CX support ticket and they investigating this internally as the issue appears to be a global one. I have provided them with some logs so I hope they will come up with a solution soon. My advise to anyone with this issue its to temporarily disable encryption from the SBC. change the SecurityMode=1 to SecurityMode=0 in the SBC config file and restart the sbc service . I suspect we will see a new SBC build soon to fix this. I hope this has been helpful for others. Additional Update Here are instructions from 3CX Support for the workaround on windows and Linux Hello all, Here are details on how to disable the encryption so you can bypass the issue for now Windows SBC Stop the 3CX SBC Service from the Windows Services. From the start menu find "Notepad", right-lick and select "Run as Administrator". Find line: SecurityMode = 1 and change to: SecurityMode = 0 Save the file. Restart the SBC service. Allow up to 10 minutes for the phone to re-register. Debian or Raspberry Pi SBC Access the SBC machine via SSH and switch to the root user. Type: service 3cxsbc stop Type: nano /etc/3cxsbc.conf Find line: SecurityMode = 1 and change to: SecurityMode = 0 Save the file by pressing Ctrl + X, then press 'y', then hit Enter. Type: service 3cxsbc start Allow up to 10 minutes for the phone to re-register. We apologize for the inconvenience that his has caused you and we will try to solve this as soon as possible.