Create transfer only mailboxes to match your extension plan. So, if you have extensions that are 2xxx and 3xxx, create a transfer-only mailbox 2000 and 3000, Then callers can dial any valid extension number and the MLAA will transfer to the dialed number. You can even have a mix of MLAA options. So you could have an option 2 and still dial extension 2222 because the VM will wait for a timeout (3 seconds I think) before going to the menu option.