Solved PBX Express and SBC

[woodelf]

Hello,
Due to Covid-19 and work from home, we recently took up a trial on Google cloud of PBX Express, which is working fine.
Now, we can re-open I need to get the office IP phones connected. However, the Debian SBC (I've tried both the iso and separately installing Debian 9 and then the SBC via wget) connected is not working.
Our FW is configured and allowing 5001 which I see the setup wizard using, but the wizard still says it is unable to reach the 3CX server. URL and key are confirmed and re-confirmed correct.

This leaves only a possible certificate error and since the express setup generated the certificates, could it be an express set up does not work with the SBC?

Any pointers gratefully received. Thanks.

 

[Saqqara]

Express setup will setup all the rules etc for SBC access.

SBC uses the 3CX tunnel port on udp / tcp 5090.

No router changes are required unless you block outgoing ports.

When setting up the SBC within 3CX management console, the url given to you , can you access it from a machine at home

Check the IP blacklist on the 3CX server and remove any entries

3CX installations on installing SBC - https://www.3cx.com/docs/3cx-tunnel-session-border-controller/#h.9yi5hq9vpsyu

 

[JohnS_3CX]

PBX Express takes care of certificates entirely if using a 3CX FQDN so that should not be an issue.

If your machine does not have a static IP, make sure 3CX Settings for network are set do Dynamic from the management console. The FQDN must resolve to the machine you are using.

 

[cobaltit]

SBC uses the 3CX tunnel port on udp / tcp 5090.

Just to clarify the SBC also uses 5001 the same as phones to to retrieve the configuration information. But as @Saqqara mentioned all traffic from the SBC is initiated outbound so unless you are blocking outbound traffic it should work. I'd start by confirming you can reach the management console from where ever the SBC is at (home or office) by pinging the FQDN from the SBC (to confirm proper DNS resolution) as well as trying in a browser from another device on the same network/network segment.

 

[woodelf]

I have to say a big thank you to everyone. Your assurance that the Express installation could not be the problem and that the SBC should "just work", persuaded me to try installing the SBC in a VM at home and like they say "bingo" it did indeed just work.
This confirmed it was an issue with our office FW, a Sophos UTM 9.
A quick Google and discarding all the convoluted port rules I'd tried previously, one from "oldeda" in the Sophos forum mentioned put the cloud server IP in "Sip Server Networks". I then reinstalled the SBC VM from the 3XC iso... perfect connected straight away. Phew, such a relief. Thank You.

 

[JohnS_3CX]

Glad to hear it was resolved