A switched telephone network is arranged in a manner to enable packet voice communication
between telephone terminals via multiple redundant packet switched networks. The
packet switched networks may utilize different protocols, be operated by different
entities, and have primary functions other than voice communication. One example
of such a network may be internetworked networks, such as the Internet. One example
of an alternate packet switched network may be a network whose primary function
is control of a circuit switched telephone network. The common channel interoffice
switching system (CCIS) of a public switched telephone network (PSTN) is one such example.