We only need to model the items that we wish to manage so it is important to list those items before we create the model. I am going to assume that, in no particular order, we will want to manage the following items:
The PBX itself, at least to disable and enable it.
The telephone and trunk interfaces, to find how many are fitted, whether they are enabled or disabled, and to get statistics about their usage.
The processor card, to find out about the amount of disk space remaining, the status and statistics of the Ethernet port, etc. Note that we must prevent the operator from disabling the Ethernet port because this will break his or her own management connection and make the PBX unmanageable.
The operating system and application software running on the processor card.
The diagnostic tests, to invoke them manually and to retrieve results.
The telephony service, to create groups of telephones for assigning incoming calls and to enable or disable the access of particular telephones at particular times of the day to outgoing trunk lines. The basic telephony statistics are also included in this service.
The voice mail service, to enable and disable access to voice mail for particular telephones and set individual limits on the disk space available for each voice mail user .
The users, to set passwords, etc.