I have a customer with a newly deployed CUCM 6.1 with Unity 5. They are getting a 5 sec silence before connecting to Unity on call forward no answer. When you call VM pilot or hit msg icon on phone, greeting kicks in right away with no delay so I think the issue is within CUCM. Anyone run into this?
Looks like there are several ES releases that fix this problem. It's also fixed on Unity 7.
Hope this helps.
If they are using Unity 5, then they probably have Phone View turned on. Before the greeting starts, it is trying to turn on the XML page on the phone to tell the user someone is leaving them a message. I have it turned off on my implementations because I have not checked recently to see if Cisco ever released and ES to fix it.
But you can check the UTIM settings on Unity and see if it is running.