All VM boxes are set up through extensions in the FreePBX.
In many cases, we like to remove the dependence so that a VM box can be created alone and can be assigned to other extensions.
1) When we have outside agents and who only need an VM box. Wtth this function, we can free up the resources (number planning) of the extensions).
2) If I have 2 locations. It will be nice if one voice mail left and extensions at both locations can light up. This can be achieved through creating an independent VM box and assigning the same VM box to each of the extensions at the 2 locations. When using either one to check voice mail, the lights on both extension will go off. This can allow users to proactively monitor the voicemail activities.
3) Allow a voice mail box to automatically "copy" or "remove" received voice mails to other voice mail boxes. This is very useful to easily send an announcement to a group of users.
To achieve these, the key is to remove the dependence of VM on extensions. There is a need to creat a module for VM alone. After a VM box is created, it can be asssigned to one extension or multiple extensions.