One items we find often is complaints from customers that voicemails were not returned. Our old system was REALLY bad at handling these (Mitel/Shoretel on premise), you had to dig through engineering logs to try and pull out of a wav file was created and you could tell when the file was deleted, but not by which extension, etc, etc. Telling it was created (even with Brightmetrics as an add on product which was a great product) was difficult and time consuming.
So it would be nice to add these features, and you could create a lock for the account in scenarios where you want to keep this feature from being accessed, as some of your customers may not want it.
1. The administrator should have a way to report if a voicemail was created... probably right in the standard logs or a new log, searching by extension and/or caller ID of the caller.
2. Actually archive the voicemail, or a process to automatically download the files for the administrator to have a look back period (our faxing solution is 60 days and that works well, but you could treat this just like call recording and charge for storage, etc., that is all practical).
3. The ability to tell when the file was deleted and by which extension on shared voicemail boxes.
4. (very fancy!) A way to delegate a local manager to have this access for a given set of extensions.
5. A way to export results of a search to a PDF or a zip file or something that can be given to managers to work from.
6. (again very fancy!) A way to tell how long the message was LISTENED to prior to being deleted. We could actually see in Mitel/Shoretel logs that the message was played at the phone for (for example) 10 seconds, when it was a 40 second message, then deleted. That was easy to show an employee never listened to the whole message before deleting it. When we could show that happened with 20 messages, we would know that management needed to correct those actions, etc.
This gives administrators at least the ability to give results to managers to show what has been happening with voicemails, etc.
We have a few of those features with our faxing solution... it also happens there (we don't use Ring Central faxing now, but it would be a similar need for other clients you have I'm sure).