Have you seen this CUCM WebDialer Developer Guide?
In addition, the Cisco DevNet Community has more WebDialer information - you just need to search:
I hope this helps,
Moderator for Cisco Customer Communities
Thanks Kelli, Sure I found that. And i still do not understand what happens. For 4 years, the system is working on 4 different CUCM cluster and one failed three month ago.
It seems no change were made (but..), it has been completely restarted; I want to find a log or something to understand what happens.