Patent ID: 9749904
Date: 2017-08-29
CPC Classifications: H04L,H04W

Claim:
1. An Interworking Function (IWF) system for converting between SGs protocol of visited network Mobile Management Entity (MME) and Mobile Application Part (MAP) protocol of a Home HLR/HSS to facilitate an International Mobile Subscriber Identity (IMSI) attach procedure, and enabling voice and SMS services for an end user device to roam into Greenfield LTE networks without legacy 2G/3G networks and without CSFB capabilities, the Interworking Function system comprising a processor and a memory containing computer-executable instructions that when executed by the processor perform a method comprising: upon receiving SGs Update Location Request from an MME located in a visited Greenfield LTE network without legacy 2G/3G networks and without CSFB capabilities, converting the SGs Update Location Request into a MAP Update Location Request and sending the MAP Update Location Request to the Home HLR/HSS based on SS7 routing mechanism; upon receiving the MAP Update Location Response from the Home HLR/HSS, converting the MAP Update Location Response into an SGs Update Location Response and relaying the SGs Update Location Response to the visited MME; upon receiving voice call setup signaling from the Home HLR/HSS, interrogating a Voice Switch for Mobile Station Roaming Number (MSRN) and responding to the Home HLR/HSS; transmitting MSRN to the user device, thereby enabling the user device to access voice call services in the Greenfield LTE network without legacy 2G/3G networks and without CSFB capabilities; upon receiving SMS route query signaling from the Home HLR/HSS, responding with an Interworking Function Global Title address as the visited Mobile Switching Center (MSC) address; and upon receiving an SMS terminating message from a Short Message Service Center (SMSC), converting the SMS into SIP signaling and routing the SIP signaling to an IP Multimedia Subsystem (IMS) system for delivery to the end user device.