Patent ID: 9137200
Filing Date: 2015-09-15
Classification: H04L

Abstract:
1. A method for operating a call originating P-CSCF node for an Interactive Connectivity Establishment (ICE) based network address translation (NAT) traversal in a communications network including an IP Multimedia Subsystem (IMS), a first user equipment (UE), and a second UE, the method comprising: receiving a SIP Invite message originating from the first UE, the SIP Invite message comprising candidate address information for the first UE; and performing operations as follows when a server reflexive candidate address for the first UE is present in the candidate address information for the first UE and a relay candidate address for the first UE is not present in the candidate address information for the first UE: forwarding the received SIP Invite message to the further IMS node for routing the SIP Invite message to the second UE when the server reflexive candidate address for the first UE is not present in the candidate address information for the first UE or the relay candidate address for the first UE is present in the candidate address information for the first UE; and wherein the candidate address information for the first UE is for use by the second UE when performing ICE operations; receiving a SIP Invite response message originating from the second UE, the second UE is behind a terminating IMS AGW node, the SIP Invite response message including candidate address information for the second UE; and performing operations as follows when a server reflexive candidate address for the second UE is present in the candidate address information for the second UE and a relay candidate address is not present in the candidate address information for the second UE: wherein the first UE is behind a first NAT device, the first NAT device being connected between the originating IMS AGW node and the first UE, the method further comprising instructing the originating IMS AGW node to perform address latching towards the first UE for discovering the transport address the first NAT device uses for the first UE; and wherein the second UE is behind a second NAT device, the second NAT device being connected between the terminating IMS AGW node and the second UE, the method further comprising instructing the originating IMS AGW node to perform address latching towards the second UE for discovering the transport address the second NAT device uses for the second UE.