Virtual PBX based on SIP and feature servers

摘要

Modular internet telephony feature servers allow individual users to manage internet telephone calls. Modular internet telephony feature servers may be used in a hierarchical internet telephony system in which a higher tier internet telephony feature server forwards telephone calls to one or more lower tier internet telephony feature servers, and each lower tier internet telephony feature server is configurable separately from the higher tier internet telephony feature server and from other lower tier internet telephony feature servers to direct telephone calls received from the higher tier internet telephony feature server.