Multiple Namespace Precedence Order in IMS Priority Call Handling
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Solution Overview
Problem
Current IMS networks lack standardized solutions for maintaining uniform priority across network elements when multiple namespaces are present in SIP Resource-Priority headers, particularly in priority and emergency calls, and there is a need for defined values for DIAMETER Rx interface AVPs to ensure consistent namespace usage.
Innovation Solution
The introduction of a Multiple Namespace Precedence Order (MNPO) namespace in the SIP Resource-Priority header allows the originating P-CSCF to determine a uniform priority treatment by selecting the namespace with the highest precedence order, which is then used to fill Reservation-Priority and Multimedia-priority services AVPs in the DIAMETER Rx interface signaling, ensuring consistent priority handling across all network elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple namespaces are present in the SIP Resource-Priority header, then the system can support multiple priority schemes, but it becomes unclear which namespace to use for determining call priority
Solution Approach 1:
The P-CSCF determines the precedence order of multiple namespaces in advance and stores this information in a configuration table before call processing. When multiple namespaces are present in the Resource-Priority header, the P-CSCF consults this pre-established precedence order to automatically select the appropriate namespace, eliminating the need for real-time decision-making and ensuring consistent priority determination across all network elements.
2Loss of information
If the originating P-CSCF determines priority based on multiple namespaces, then comprehensive priority information is available, but consistency with terminating P-CSCF and other network elements cannot be ensured
Solution Approach 1:
The invention establishes a uniform namespace selection mechanism where all network elements (originating P-CSCF, terminating P-CSCF, and other downstream elements) use the same precedence order to determine which namespace to apply. This ensures that the same namespace is selected consistently across the entire call path, maintaining homogeneous priority treatment despite the presence of multiple namespaces with different priority schemes.
3Adaptability or versatility
If no standardized solution is provided for multiple namespace handling, then network operators have flexibility in implementation, but uniform priority handling across different operators' networks cannot be achieved
Solution Approach 1:
The invention creates a universal mechanism for handling multiple namespaces that can be applied across different network operators' IMS networks. By defining a standardized approach where the P-CSCF determines and uses a precedence order for namespaces, the solution provides a multi-functional framework that works for both originating and terminating networks, ensuring consistent priority handling across operator boundaries while allowing operators to configure their own namespace precedence orders.
Data Source
AI summary
A method of call handling when multiple namespaces are present for a call of a priority or emergency call type initiated by a subscriber of a wireless network includes: obtaining, by an originating Proxy Call Session Control Function (P-CSCF), a predetermined precedence order for the multiple namespaces; retrieving, by the originating P-CSCF, each namespace and associated priority from the subscriber's Registration Context; inserting, by the originating P-CSCF, a SIP Resource-Priority header for each namespace and associated priority; and inserting, by the originating P-CSCF, an additional SIP Resource-Priority header with an additional specified namespace (Multiple Namespace Precedence Order (MNPO)) and priority value identifying the predetermined precedence order for the multiple namespaces. The originating P-CSCF uses the namespace with the highest precedence order to select the appropriate values to fill in Reservation-Priority Attribute-Value Pair (AVP) and Multimedia-priority services (MPS) Identifier AVP in Rx interface signaling to a Policy and Charging Rules Function (PCRF).