Best way to avoid downtime during version upgrades?

[imabev]

Is there a way to keep 3CX phone system up 100% suring a version upgrade? Most major upgrades have involved uninstalling/reinstalling 3CX. Would this be possible with the enterprise version? Switch to secondary server, upgrade primary server, switch back to primary. Or would this not work because the versions need to match for failover?

The other concern is maintaining uptime during server patching but not as critical as version upgrades.

 

[cobaltit]

So with the current 'failover' the versions matching don't really matter if you will be doing them back to back. The 'failover' is basically a scheduled backup on the primary/active and then scheduled restore on the secondary/backup. That would be the closest you will get to 100% uptime during the upgrade. It would require custom templates for the phones to be configured to register to both servers as well as a way to have your dialtone work across both servers.