T 3.82 Incorrect configuration of VoIP middleware

A VoIP-based telephone system can be affected by faulty configurations in the same manner as a circuit-switching telephone solution. Possible errors in the configuration range from incorrect telephone subscriber to telephone number assignments to a loss of the availability of the telephone infrastructure. Even rather minor errors, such as a name spelled incorrectly in the telephone book, cannot be ruled out.

Furthermore, certain users can be granted calling privileges or have these privileges taken away on the telephone system. Examples of such privileges include the ability to call foreign countries or to call service numbers that charge a fee. An incorrect setting here can make misuse possible, for example when telephones accessible to the public are granted authorisation to make foreign calls.

When using VoIP, several systems need to be integrated as a rule. If SIP is used as the initialisation protocol, then systems such as registrars, SIP proxy servers, and location servers are needed for communication. When changes need to be made, then all systems need to be adapted to the changes, possibly resulting in errors in the configurations. Even when all services are located on a single computer system, they often need to be configured individually. An incorrect change on just one system could possibly result in the inability to use the entire telephone infrastructure.

When VoIP is used, a classic answering machine is generally not used, and a voice mail is sent instead when the user is absent or unavailable. The voice mail often comes in the form of an e-mail with a voice message attached in an audio file. If the e-mail address is not entered correctly in the configuration, the intended recipient will not receive the incoming messages. The messages may even be sent to the wrong recipient instead.

In addition to the actual VoIP telecommunication systems, the routers and switches operating in the lower network layers also need to be configured. To prevent delays in communication, many devices can be configured to assign a higher transmission priority to VoIP messages. Errors in the configuration in this case can lead (in the worst-case scenario) to the complete failure of the network.