A system and unified method of address resolution in an IP-based network. A Resolver determines whether an input address is a URL/URI, and if so, extracts a domain name. If the input address is an E.164 number, the Resolver converts the E.164 number into a domain name in ENUM format. The Resolver then sends a domain name query to a DNS which, if able, returns the IP address for either a Global MGCF or a destination server along with a supported Application protocol. If the DNS is unable to perform the translation, or the Application protocol returned is not supported by the requesting application, the Resolver sends a domain name query to an extended Location Server (LS) to obtain an IP address of a gateway function capable of interfacing with the destination server.