IMS Application Server Call Presentation for Unregistered Terminals

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Solution Overview

Problem

In IMS networks, when a call is received, terminals not yet registered in the core network cannot take the call, as the prioritization and call presentation mechanism is already activated for registered terminals, preventing the call from being presented to newly registering terminals.

Innovation Solution

An IMS application server intercepts call presentation requests, detects the registration of terminals with a given public identity, and sends the call presentation request to newly registered terminals, allowing them to take the call without delaying network establishment and without modifying the S-CSCF servers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the prioritization and call presentation mechanism is activated for registered terminals, then registered terminals can receive calls efficiently, but newly registering terminals cannot take calls

Engineering Contradiction:

Improvecall presentation reliabilityVSAvoidterminal registration flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The application server performs preliminary actions by intercepting call presentation requests before they reach the S-CSCF, detecting terminal registration status, and proactively presenting calls to newly registered terminals. This preliminary intervention ensures both registered and newly registered terminals can receive calls without waiting for traditional prioritization processing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The application server acts as an intermediary between the S-CSCF and terminals. It receives call presentation requests from the S-CSCF, detects which terminals are newly registered, and selectively presents calls to those terminals. This intermediary role enables the system to handle both registered and newly registered terminals appropriately without modifying the core S-CSCF prioritization mechanism.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If call presentation is restricted to registered terminals only, then network establishment is faster, but newly registered terminals are excluded from receiving calls

Engineering Contradiction:

Improvenetwork establishment speedVSAvoidcall delivery capability

Core Design Contradiction:

SpeedVSProductivity

Solution Approach 1:

The application server performs preliminary detection of terminal registration status and preliminary presentation of calls to newly registered terminals before the traditional prioritization process completes. This allows the system to maintain fast network establishment for registered terminals while simultaneously ensuring new terminals receive calls without significant delay.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The call presentation process is segmented into two parallel paths: one for registered terminals through the existing S-CSCF prioritization mechanism, and another for newly registered terminals handled by the application server. This segmentation allows both paths to operate independently and efficiently, ensuring call delivery capability is not compromised by the registration timing.

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If the S-CSCF prioritization mechanism is modified to include newly registered terminals, then call delivery to new terminals is enabled, but core network complexity increases

Engineering Contradiction:

Improveterminal registration flexibilityVSAvoidcore network complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The application server serves as an intermediary that handles the complexity of detecting newly registered terminals and presenting calls to them. By placing this logic in the application server rather than modifying the S-CSCF, the core network remains relatively simple while still achieving the desired adaptability for new terminal registration.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The complex logic for detecting newly registered terminals and managing their call presentation is extracted from the S-CSCF and placed in the application server. This extraction reduces the complexity burden on the core network while enabling the system to handle newly registered terminals effectively.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentEP2429145B1Method for displaying a call in an IMS network and application server suitable for implementing said method

Publication Date: 2017.04.12 ORANGE SA

AI summary

The method involves receiving a request of display of a call (E73) of a terminal (T1), and obtaining a public identity of the terminal and a domestic gateway (HGW), from the request. The registration of another terminal (T2) having the public identity, is detected in an internet protocol (IP) multimedia subsystem (IMS) network by regularly interrogating a serving call state control function (S-CSCF) entity. The display request of the call is sent to the latter terminal, where the request is a session initiation protocol (SIP) INVITE message having a contact address of the latter terminal. Independent claims are also included for the following: (1) an application server for use in a IMS network (2) a computer program comprising a set of instructions for performing a call displaying method (3) a storage medium comprising a set of instructions for performing a call displaying method.