Patent ID: 9015327
Filing Date: 2015-04-21
Classification: H04L

Abstract:
1. A method, comprising: receiving, at a terminating call session control function (CSCF) server associated with a terminating communication device, a first session initiation protocol (SIP) invitation message comprising a first fully qualified domain name for identifying an originating communication device; receiving, by the terminating CSCF server, a second SIP invitation message to the terminating CSCF server, wherein the second SIP invitation message comprises a second fully qualified domain name for identifying the originating communication device and an identity of a terminating CSCF server, which are received from an interrogating CSCF server according to a request from the originating CSCF server comprising a telephone number; transmitting, by the terminating CSCF server, an A type query and an AAAA type query associated with the second fully qualified domain name to a domain naming server (DNS) server responsive to receiving the second SIP invitation message, wherein the A type query corresponds to a query for an IP Version 4 (IPv4) address, and wherein the AAAA type query corresponds to an IP Version 6 (IPv6) address; receiving, by the terminating CSCF server, an answer associated with one of the A type query, the AAAA type query, or a combination thereof, wherein the answer comprises one of an IPv4 address, an IPv6 address; and analyzing, by the termination CSCF server, the answer that is received to determine an answer combination; transmitting, by the terminating CSCF server, a first response message comprising the IPv4 address if the answer combination comprises the IPv4 address with a first non-error indicator and the IPv6 address with a first error indicator; transmitting, by the terminating CSCF server, a second response message comprising the IPv6 address if the answer combination comprises the IPv4 address with a second error indicator and the IPv6 address with a second non-error indicator; and determining, by the terminating CSCF server, that the originating communication device comprises a dual stack device if the answer combination comprises the IPv4 address with the first non-error indicator and the IPv6 address with the second non-error indicator.