Is your Cisco Unity integrated with MS Exchange and AD? I had a similar issue related to process load on the Exchange/AD server.
On the surface, Exchange/AD appeared to be working just fine, but the underlying connection would take longer and longer to prompt for login (AD) and query Exchange for new messages.
Resetting the Exchange/AD server would fix the issue for a while, but eventually the issue would return.
I tried many a dozen different adjustments to the Exchange/AD server, but wasn't able to isolate the cause. I ended up moving to Unity Connection and mostly removing all of the MS components as a long term fix.
I couldn't completely remove Exchange/AD because of other dependencies, but now I can reset it without interrupting voicemail services.
Brian
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