A Voice-over-Internet protocol (VOIP) communications network system that enables direct-dialed (single-stage) access to the Internet Protocol (IP) network from the circuit-switched network. Specifically, the VOIP network system includes a VOIP service implemented on a communications system which, after a customer number has been registered for the service, automatically recognizes calls from the registered customer's telephone number and determines if the call can be routed as a VOIP call over the IP network. In embodiments of the present invention, the customer can register for the VOIP service by selecting both a provider (PIC) and a calling plan or by only selecting a provider. The system can be implemented to handle intra-state, inter-state and international voice-band calls (for example, regular telephone calls, facsimile transmissions and modem initiated calls) using standard circuit-switched telephone lines, cable, twisted pair, digital subscriber line (DSL) and wireless.