IMS Inbound Roamer Call Routing via Database Query
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Solution Overview
Problem
Current IMS routing procedures fail to efficiently route originating calls from inbound roaming users, leading to incorrect or failed call routing due to unknown local numbering plans and overlapping service numbers, especially when users dial service numbers or local numbers during roaming.
Innovation Solution
Implementing a mechanism in the IMS network that queries a database to determine if the called party number is allowable in the access network, modifying SIP INVITE request messages to include routing indications, and using network nodes like P-CSCF or IBCF to route calls correctly by setting phone context parameters or routing indications within the SIP INVITE request messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current IMS routing procedures are used for inbound roamers, then the routing process is simple, but call routing fails or is incorrect due to unknown local numbering plans and overlapping service numbers
Solution Approach 1:
The patent introduces a database as an intermediary component between the IMS network nodes and the call routing process. This database stores local numbering plans and service number information, allowing the network to query and determine the correct routing destination without increasing the complexity of the routing process itself. The database acts as a mediator that resolves the conflict between simple routing procedures and accurate call routing by providing the necessary routing information on demand.
Solution Approach 2:
The patent implements preliminary action by pre-populating the database with local numbering plans and service number information before routing decisions are made. The network nodes query this pre-prepared database to determine whether to route calls to the access network or home network, rather than performing complex real-time analysis. This preliminary preparation of routing information enables accurate call routing without adding complexity to the actual routing process.
2Reliability
If the network queries a database to determine number allowability, then call routing accuracy improves, but network processing time and complexity increase
Solution Approach 1:
The database is pre-populated with local numbering plans, service numbers, and routing information before the call routing process begins. This preliminary preparation allows the network nodes to quickly query and retrieve routing decisions without performing complex real-time analysis. The patent implements this by having the database contain pre-defined rules and information about which numbers are allowable in the access network, enabling fast lookup and decision-making during call setup.
Solution Approach 2:
The patent replaces complex mechanical routing analysis with a database query system. Instead of performing intricate real-time analysis of numbering plans and service numbers, the network nodes simply query the database which has already processed and stored the routing information. This substitution of the mechanical routing analysis system with a database query system significantly reduces processing time while maintaining high routing accuracy.
3Reliability
If routing indications are added to SIP INVITE messages, then call routing to access network improves, but signaling message complexity increases
Solution Approach 1:
The patent applies local quality by adding routing indications only to specific SIP INVITE messages that require access network routing, rather than modifying all SIP messages uniformly. The network nodes selectively insert routing indications based on database query results, modifying only the necessary signaling messages. This localized modification approach improves call routing success for inbound roamers while minimizing the increase in overall signaling message complexity.
Solution Approach 2:
The patent extracts the routing decision logic from the complex SIP signaling process and places it in a separate database. The SIP INVITE messages only carry the essential routing indication parameter, while the complex routing logic and number validation rules are extracted and stored in the database. This separation reduces the complexity embedded in each signaling message while maintaining high routing accuracy through the database-driven approach.
Data Source
AI summary
Network nodes for an access network and a home network of a first UE are described for use when routing an originating call from the first UE in the access network including an IMS network. A network node receives a SIP INVITE message associated with the originating call from the first UE, and including a called party number associated with the call. The network node determines whether the first UE is visiting the access network and whether the called party number is associated with the access network. The network node determines whether the called party number is allowable in the access network. The network node modifies and transmits the received SIP INVITE message towards a home network of the first UE to cause the home network to route the originating call to the access network.