A method and an apparatus for processing a session request in an Internet Protocol (IP) network are disclosed. For example, the method receives a session request, and queries an tElephone NUmbering Mapping (ENUM) server for a called party of the session request. The method determines if at least one Naming Authority Pointer (NAPTR) resource record associated with the called party is received from the ENUM server, and forwards the session request to a circuit switched network if the at least one NAPTR resource record is not received from the ENUM server. The method determines a Session Description Protocol (SDP) value of the session request if the at least one NAPTR resource record is received from the ENUM server, and processes the session request in accordance with the SDP value if the at least one NAPTR resource record is received from the ENUM server.