Routing methods and systems using ENUM servers internal and external to a service provider network

A method of processing a Voice over Internet Protocol (VoIP) call from a first service provider to a destination telephone number, the destination telephone number served by a second service provider other than the first service provider, the method comprising:

• sending a Session Initiation Protocol (SIP) INVITE message from an originating switch to a first SIP server of the first service provider;
• determining, by the first service provider, an address of a telephone number mapping (ENUM) server of the second service provider;
• querying, by the first service provider, the ENUM server of the second service provider, and receiving a Uniform Resource Identifier (URI) associated with the destination telephone number in response thereto;
• querying, by the first service provider, a Domain Name Service (DNS) server based on the URI, and receiving an Internet Protocol (IP) address of a second SIP server of the second service provider in response thereto;
• and
• using the first SIP server and the second SIP server to set up a bearer path for the VoIP call between the originating switch and a destination switch.

A method of processing a Voice over Internet Protocol (VoIP) call from a first service provider to a destination telephone number, the destination telephone number served by a second service provider other than the first service provider, the method comprising:

• sending a Session Initiation Protocol (SIP) INVITE message from an originating switch to a first SIP server of the first service provider;
• querying, by the first SIP server, a first telephone number mapping (ENUM) server of the first service provider to attempt to resolve the destination telephone number;
• querying, by the first ENUM server, a database server and receiving a carrier identifier of an owner of the destination telephone number in response thereto;
• determining an address of a second ENUM server of the second service provider based on the carrier identifier;
• querying, by the first service provider, the second ENUM server of the second service provider, and receiving a Uniform Resource Identifier (URI) associated with the destination telephone number in response thereto;
• querying, by the first service provider, a Domain Name Service (DNS) server based on the URI, and receiving an Internet Protocol (IP) address of a second SIP server of the second service provider in response thereto;
• and
• using the first SIP server and the second SIP server to set up a bearer path for the VoIP call between the originating switch and a destination switch.

A method of processing a Voice over Internet Protocol (VoIP) call from a first service provider to a destination telephone number, the destination telephone number served by a second service provider other than the first service provider, the method comprising:

• sending a Session Initiation Protocol (SIP) INVITE message from an originating switch to a first SIP server of the first service provider;
• determining, by the first service provider, an address of a telephone number mapping (ENUM) server of a third service provider other than the first service provider and the second service provider;
• querying, by the first service provider, the ENUM server of the third service provider, and receiving a Uniform Resource Identifier (URI) associated with the destination telephone number in response thereto;
• querying, by the first service provider, a Domain Name Service (DNS) server based on the URI, and receiving an Internet Protocol (IP) address of a second SIP server of the second service provider in response thereto;
• and
• using the first SIP server and the second SIP server to set up a bearer path for the VoIP call between the originating switch and a destination switch.

A method comprising:

• sending a Session Initiation Protocol (SIP) INVITE message from an originating switch to a SIP server;
• querying, by the SIP server, a first telephone number mapping (ENUM) server to attempt to resolve a destination telephone number;
• querying, by the first ENUM server, a database server and receiving a carrier identifier of an owner of the destination telephone number in response thereto;
• determining a domain name associated with the carrier identifier and passing the domain name to the SIP server;
• querying, by the SIP server, an internal Domain Name Service (DNS) server based on the domain name;
• querying, by the internal DNS server, an external DNS server based on the domain name and receiving an Internet Protocol (IP) address of a second ENUM server in response thereto;
• passing the IP address of the second ENUM server from the internal DNS server to the SIP server;
• querying, by the SIP server, the second ENUM server and receiving a Uniform Resource Identifier (URI) associated with the destination telephone number in response thereto;
• and
• using the SIP server to set up a bearer path between the originating switch and a destination switch based on the URI.

A system for processing a Voice over Internet Protocol (VoIP) call from a first service provider to a destination telephone number, the destination telephone number served by a second service provider other than the first service provider, the system comprising:

• a network of the first service provider, the network comprising an originating switch, a first Session Initiation Protocol (SIP) server, a first telephone number mapping (ENUM) server, and a database server, the network to:
• send a SIP INVITE message from the originating switch to the first SIP server;
• query, by the first SIP server, the first ENUM server to attempt to resolve the destination telephone number;
• query, by the first ENUM server, the database server and receive a carrier identifier of an owner of the destination telephone number in response thereto;
• determine an address of a second ENUM server of the second service provider based on the carrier identifier;
• query the second ENUM server of the second service provider and receive a Uniform Resource Identifier (URI) associated with the destination telephone number in response thereto;
• query a Domain Name Service (DNS) server based on the URI and receive an Internet Protocol (IP) address of a second SIP server of the second service provider in response thereto;
• and
• negotiate with the second SIP server to set up a bearer path for the VoIP call between the originating switch and a destination switch.

A computer-readable medium having computer-readable program code that causes a network comprising an originating switch, a Session Initiation Protocol (SIP) server, a first telephone number mapping (ENUM) server, a database server, and an internal Domain Name Service (DNS) server to perform acts of:

• sending a SIP INVITE message from the originating switch to the SIP server;
• querying, by the SIP server, the first telephone number mapping (ENUM) server to attempt to resolve a destination telephone number;
• querying, by the first ENUM server, the database server and receiving a carrier identifier of an owner of the destination telephone number in response thereto;
• determining a domain name associated with the carrier identifier and passing the domain name to the SIP server;
• querying, by the SIP server, the internal DNS server based on the domain name;
• querying, by the internal DNS server, an external DNS server based on the domain name and receiving an Internet Protocol (IP) address of a second ENUM server in response thereto;
• passing the IP address of the second ENUM server from the internal DNS server to the SIP server;
• querying, by the SIP server, the second ENUM server and receiving a Uniform Resource Identifier (URI) associated with the destination telephone number in response thereto;
• and
• using the SIP server to set up a bearer path between the originating switch and a destination switch based on the URI.