In (Figure 4.41) it is possible to see the registered IPBrick VoIP clients (IP telephones, workstations + softphone). In section Machine Management you find the description of the menu to insert the VoIP machines.
It is also possible to register phones in:
Advanced Configurations - Telephony - Registered Phones
This option is valid, if it isn't necessary to attribute a specific IP address to the phone. It is possible to add a phone just by filling the field relating the name and the access password. This assuming that DNS is working correctly.