Registration Proxy Emulating S-CSCF for IMS Access
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Solution Overview
Problem
The existing proposal for 'Short Message Service over IMS' does not fully utilize SIP capabilities, requiring mobile nodes to be IMS registered to receive SMS messages, which many SIP-capable nodes cannot achieve due to stringent IMS registration requirements.
Innovation Solution
A registration proxy is introduced to effect IMS registrations on behalf of mobile nodes, either automatically when they establish a network connection or after determining their registration capability, by emulating user equipment or a serving call session control function, using SIP REGISTER requests to facilitate IMS registration in the IMS network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mobile nodes are required to be IMS registered to receive SMS messages, then SMS service reliability is improved, but device compatibility deteriorates because many SIP-capable nodes cannot achieve IMS registration
Solution Approach 1:
The patent introduces an application server as an intermediary component that bridges the gap between SIP-capable mobile nodes and the IMS registration requirement. The application server receives SMS messages intended for mobile nodes and forwards them through alternative pathways that do not require the mobile node to be IMS registered, thus maintaining SMS service reliability while expanding device compatibility to include SIP-capable nodes that cannot perform IMS registration
Solution Approach 2:
The patent segments the SMS delivery process into separate functional components: message reception at the application server, message storage in a message repository, and message forwarding to the mobile node. This segmentation allows the registration requirement to be applied selectively to different parts of the system, enabling SIP-capable nodes to receive messages without requiring full IMS registration capability
2Reliability
If IMS registration requirements are made stringent to ensure proper service delivery, then service quality is improved, but the number of capable mobile nodes decreases
Solution Approach 1:
The application server acts as a mediator that maintains service quality for IMS-registered nodes while simultaneously enabling service delivery to non-IMS-registered SIP-capable nodes. It implements different handling paths: for IMS-registered nodes, standard IMS procedures are used; for non-registered nodes, alternative delivery mechanisms are employed, thus preserving service quality across diverse node capabilities
Solution Approach 2:
The patent applies partial action by requiring IMS registration only for nodes that need full IMS service capabilities, while allowing SIP-capable nodes without registration to receive basic SMS services. This partial application of registration requirements expands the total number of capable mobile nodes while maintaining adequate service quality for registered nodes
Data Source
AI summary
An application server provides communication services via a packet-switched network to mobile nodes based on their respective registrations in a registry, such as a home subscriber server (HSS) or domain name server (DNS). A registration proxy may be used to effect a registration in the registry on behalf of a mobile node when the mobile node lacks sufficient capability to effect the registration itself. The registration proxy may perform this function after receiving a notification that the mobile node is connected to the packet-switched network and after querying a capabilities server to determine that the mobile node lacks sufficient registration capability. To effect a registration in an HSS, the registration proxy may emulate either a serving call state control function (S-CSCF) or user equipment (UE).