Voice mail boxes (VMB) are among the value-added services provided by network operators for voice-oriented applications. A voice mail box is a voice memory that provides access options via the analoguetelephone network, ISDN or via the mobile networks.
The function of a voicebox is similar to that of an answering machine, with the difference that the subscriber does not have his own device, but the functionality is provided to him by the network operator or service provider. A voicebox makes it possible to leave a spoken message for a subscriber who cannot be reached. If the subscriber is not reachable, the voicebox accepts the calls, the incoming messages (ICM). The messages are stored centrally by the service provider. They can then be retrieved as Outgoing Messages (OGM) from any telephone line by dialing a specific number and entering an identification number. The ID number is used to protect against unauthorized interception of the messages.
The voice messages are announced by the service provider with the date and time and, in the case of call number transmission, with the caller's call number. The service provider offers a direct callback to the specified call number.