I struggled a couple of weeks before I came across a great post about installing CUCM on a vmware workstation. I needed this for CIPT1 labs.Strangely, the website has been taken down due to a hacking attempt.
Well, everything seemed to work fine until the NTP configuration step. Here, I’ve discovered that , when configuring NTP server, make sure your guest machine can connect to the internet and check the public NTP server.
So if you have a computer firewall, disable it.
You can find a list of public NTP servers here