Symptom:
On the /cucmlookup and /zones pages the SIP status of neighbour zones to UCMs is shown. On the /editzones it has the State.

Edge neighbour zones towards UCMs are configured with Monitor peer status set to "No".

Provided the VCS can resolve the Peer address to an IP address it shows the status / state as "Active". 

An administrator I might be forgiven for assuming that this meant that the VCSc could happily communicate with the UCM, and indeed was doing so.

For edge zones: 
Either the VCSc should say something like "address resolvable" instead of "Active", or it should actually try to communicate with the UCM to determine that as a minimum establish a connection to the server. This would help a little with diagnosing routing issues, invalid DNS settings, certificate problems (for TLS connections) etc.

This could be achieved by setting the Monitor peer status to "Yes".

Otherwise the VCS admin won't see a problem until an Edge device fails to connect.

Conditions:
VCS / Expressway running MRA