Team,
I just confirmed that Ring Group DOES in fact show up in work applications. The only reason I would think that it does not is if 1) there is a communication/firewall restriction blocking that communication (kinda outside chance here) OR the yse has no access to the ring group voice mail in which it would not show up on their phone.
I would recommend testing on a less restrictive network such as a home without any vpn running or on the Mobile LTE service with no vpn running. after you verify that they do have access to voicemail. There is NO option to say on phone or work only for notifications.
Another option is a different nurse listens to the voicemail and deletes it. the VM for Ring Group is NOT duplicated to all users, it is a "single" message and once one person listens and processes that message the message is processed for ALL members of the group. Does that make sense?