Reverse ENUM based routing for communication networks

A method of routing a call between communication networks, the method comprising the steps of:

• establishing a reverse ENUM DNS server containing a table of NAPTR records that associate E.164 telephone numbers with SIP URIs;
• routing a call to a callee from an originating PSTN system to a first gateway;
• sending an ENUM query containing an E.164 telephone number for the callee to a first ENUM DNS server associated with the first gateway;
• returning an SIP URI associated with the E.164 telephone number from the sending step by the ENUM DNS server to the first gateway;
• routing the call to a second gateway through the VoIP communication network;
• launching a reverse ENUM query containing the SIP URI to the reverse ENUM DNS server associated with the second gateway;
• looking up at least one E.164 telephone number associated with the SIP URI from the launching step;
• returning the at least one E.164 telephone number from the looking up step from the reverse ENUM DNS server to the second gateway;
• and
• routing the call from the second gateway to the returned at least one E.164 telephone number of the callee in the terminating PSTN system.

A system for routing a call between communication networks, the network comprising:

• a first ENUM DNS server that contains a table of NAPTR records that associate identifiers with E.164 telephone numbers;
• a reverse ENUM DNS server that is established containing a table of NAPTR records that associate E.164 telephone numbers with identifiers;
• an originating PSTN system operable to originate a call to a callee;
• a first gateway associated with first ENUM DNS server and operable to receive the routed call from the originating PSTN system and send an ENUM query containing an E.164 telephone number for the callee to the first ENUM DNS server, which is operable to return an identifier associated with the E.164 telephone number to the first gateway, whereupon the first gateway routes the call through the VoIP communication network;
• a second gateway associated with reverse ENUM DNS server and operable to receive the call via the VoIP communication network and launch a reverse ENUM query containing the identifier to the reverse ENUM DNS server, which is operable to look up at least one E.164 telephone number associated with the identifier and return the at least one E.164 telephone number to the second gateway, whereupon the second gateway routes the call to the returned at least one E.164 telephone number of the callee;
• and
• a terminating PSTN system that is operable to route the call to the callee.