A real-time interface between the public switched telephone network (PSTN) and an Internet Protocol (IP) network provides voice to data and data to voice conversion between the PSTN and the IP network in a seamless process. The interface, a central communication network, performs Class 5 switching between the PSTN and the IP network, besides providing enhanced services. Receiving a call, the central communication network simultaneously routes the call to a plurality of pre-programmed numbers on the PSTN and on the IP network. The central communication network provides call screening, takes voice messages and converts them to e-mail messages, takes e-mail or facsimile messages and converts them to voice messages. Communication between a PSTN phone on a local PSTN, a computer hooked up to the IP network, a phone hooked up to the IP network by a gateway, a private branch exchange (PBX) on a local PSTN, a wireless communication system with pagers and/or cell phones hooked up to a local PSTN, and facsimile machines on a local PSTN, for example, is provided by the central communication network. Through the central communication network, a computer hooked up to the IP network can exchange voice messages and facsimile messages with a PSTN connected device and conduct conference calling with a plurality of PSTN devices.