I have a CUCM cluster mocked in the lab ready for production with one exception.
The scenario: 1 Pub and 2 Subs. I am licensed for 3 servers.
When all three servers are up, the phones do not show the pub as an acive or standby CCM. The phones register to a sub as the active CCM, and the other sub shows as standby.
If I power down one of the subs, the pub then becomes a standby.
Is this normal behaviour? If not, any ideas as to what needs to be done to correct this?
That's a normal behaviour. The IP Phone talks to primary and one standby CCM server. Any territory server comes into play only when one of them is offline.
Your CCM group would be having Sub1, Sub2 and lastly Pub that's why your are seeing Sub1 and 2 as active/standby and Pub neither active nor standby. If you want to see Pub as active, make it the first choice in CCM group. Keep in mind that's going to have all your IP Phones hooked onto Pub which is not a good practise in large deployment.