An inventory of authorized instruments is NOT documented or maintained in support of the detection of unauthorized instruments connected to the VoIP system.

Traditional telephone systems require physical wiring and/or switch configuration changes to add an instrument to the system. This makes it difficult for someone to add unauthorized digital instruments to the system. This, however, could be done easier with older analog systems by tapping an existing analog line. With VoIP, this is no longer the case. Most IPT/VoIP systems employ an automatic means of detecting and registering a new instrument on the network with the call management server and then downloading its configuration to the instrument. This presents a vulnerability whereby unauthorized instruments could be added to the system or instruments could be moved without authorization. Such activity can happen anywhere there is an active network port or outlet. This is not only a configuration management problem, but it could also allow theft of services or some other malicious attack. It is recognized however, that auto-registration is necessary during large deployments of VoIP terminals, as well as a short time thereafter, to facilitate additions and troubleshooting. This applies to initial system setup and to any subsequent large redeployments or additions. Normal, day to day, "moves, adds, and changes" will require manual registration. Since, it may be possible for an unauthorized VoIP terminal to easily be added to the system during auto-registration, the registration logs must be compared to the authorized terminal inventory. Alternately the system could have a method of automatically registering only pre-authorized terminals. This feature would support VoIP terminals that are DAA approved for connection from multiple local or remote locations. It is critical to the security of the system that all IPT /VoIP end instruments be authorized to connect to and use the system. Only authorized instruments should be configured in the system controller and therefore allowed to operate. Unauthorized instruments could lead to system compromise or abuse. A manual inventory of authorized end instruments will aid in the detection of unauthorized instruments registered to the system particularly during the period when auto-detection/registration is permitted. This will also aid in C&A efforts.