Upgrading 15.5 to v16 and migrating servers

[dcsdit]

So I have about 14 servers that are on Version 15.5 (I know, but if it aint broke don't fix it)., and I have been tasked with upgrading them to v16. The existing servers are Windows 2008R2 (all VMWARE guests), and the new servers will be Server 2016. I have put together the following process for upgrading and migrating and just want to see if it sounds good to the people who have much more experience with this:
1. Get new server ready (fully patched)
2. Install latest version of 3cx
3. Backup old server database
4. Decommission old server -- copy templates from old server to new server -- remove from domain power down.
5. Rename new server to the old server name -- also change IP to old server IP.
6. Restore/Migrate from latest backup
7. Call 3cx to get the new server activated
8. reinstall 3rd party tools (voiptools) and work with 3rd party to get activated.

I understand that step 4 and 5 will incur downtime of the phone systems, but I work for k-12 education and School is out for summer, so having a small windows of downtime is not an issue. Is there anything I am missing in these steps? Is there a better way to go about doing this?

Thanks!!!

 

[Saqqara]

You steps are slightly wrong - https://www.3cx.com/docs/upgrading-pbx-v16/.

You can not install 3CX onto new server, until you have switched off the old server - at least stop it accessing the internet. You can not have two servers running at the same time with the same license key and fqdn as the 3CX software calls home.

 

[dcsdit]

Thank you!!! I will adjust my steps.