It's hard to give you a hard number. It depends on your user requirements as well as hardware (with 4000 users, I'll assume you're using 7845 most likely). A few things to think about and recommendations:
1) Configure CUC to enable the deleted items folder --> Class of Service > Message Options > Uncheck "Delete Messages Without Saving To Deleted Items Folder"
2) Enable message-aging policies system-wide (default) and you can customize per user (if needed). You can then configure the schedule by which deleted items are purged. The default purge frequency if you enable this in conjunction with #1 as noted above is 15 days.
3) Some general notes on mailbox (assuming G.711):
Default values provide 25 minutes of audio before warning, 27 minutes of audio before send quota, and 29 minutes of audio before send/receive quota.
I generally assume the average message size is 60 - 90 seconds, but that's not official by any means.
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The short answer is that you don't.... That isn't entirely true while at
the same time it kind of is, but for the most part you don't configure
the softkeys. You enable or disable them via TCL. Here is the long
answer. Be sure to read the whole thing or e...
Topology: IP Phone > Switches > Microsoft NPS setup to forward 802.1x
proxy to > ISE 2.1 patch 3 Authentication: EAP-TLS using Cisco MIC SANs
Phone Models 802.1X support? 802.1x flavor Addtl Comment EAP-MD5 EAP-TLS
Cisco 3905 Y Y N Cisco 6911 Y Y N Cisco ...