RELATED IDEAS
Prevent Voice mails for unregistered accounts
Like preventing outgoing calls for lines with no e-911 address assigned, shut off voice mails by default until the ext. is registered to an account that can access the voice mail. this would automatically be enabled once registration is completed (default would be like the option play message and disconnect
Maybe simpler option is any unregistered account would have the play announcement set in what to do when call goes unanswered. and maybe a different messages like this phone does not have a registered voice mail setup so you cant leave a message at this time. Once the account is registered then it could auto flip to send to voice mail.
this is in fact the correct procedure as the user can not access any voice mails since they have not yet setup the password / pin so no leaving voice mail should be possible
Same thing would happen automatically when an account is set to disabled.