With the Enterprise edition (single licence which support x2 activations) I would say it works a lot better.
There is a standard fail-over option with the PRO licence however it was a real nightmare to setup and although I did achieve it there was a lot to configure (Share between systems, Windows scripts, DNS etc).
This will cover a lot of what is required for the fail-over:
https://www.3cx.com/docs/failover/ with an Enterprise licence. I have however given some additional points below:
* Ideally the environment should require SPLIT DNS:
https://www.3cx.com/docs/creating-fqdn-split-dns/
* 3CX Provided FQDN and SSL is mandatory.
* There is no Active/Active setup for 3CX failover. You can only configure it as active/ passive.
* The IP address setup should be static and configured accordingly in each PBX used.
* The Failover System will register at start-up the new IP address on your FQDN which is used for external devices to connect to (STUN, SBC, 3CXPhone, Presence).
I hope this helps.
