You should still be able to use IMAP with a hosted solution to download voicemail.. Meeting free/busy information will not work because of webdav. I think your bigger issue is, how do voicemails get from (I assume) your onsite Unity or Unity Connection to the hosted solution. The only way it can is to use SMTP forwarding to the server. The IMAP will not download the voicemails because they will not be tagged (have not tried, but may work).
If you are using Unity Connection, you could have the CUPC client connect directly the server using IMAP and play voicemails.
So getting WebDAV/OWA access would be one thing... and getting your hosted provider to set up an account with the necessary privileges to access all your users may be another difficult/impossible task.
Please remember to rate helpful posts to identify useful responses, and mark 'Answered' if appropriate!
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.