A network and method of routing a call between communication networks includes a first step of establishing a reverse ENUM DNS server containing a table of NAPTR records that associate E.164telephone numbers with identifiers. A next step includes routing a call from an originating PSTN system to a first gateway. A next step includes sending an ENUM query containing an E.164telephone number to an ENUM DNS server, which returns an identifier associated with the E.164telephone number. A next step includes routing the call to a second gateway. A next step includes launching a reverse ENUM query containing the identifier to the reverse ENUM DNS server, which looks up an E.164telephone number associated with the identifier, and returns it to the second gateway. A next step includes routing the call from the second gateway to the returned E.164telephone number in the terminating PSTN system.