Dual SIM Call Forwarding Coordination for Voice Mail Separation

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Solution Overview

Problem

Existing communication systems with dual SIM-cards cannot effectively differentiate and manage voice mail functions for separate business and private lines, leading to incorrect forwarding of calls when one line is active but not reachable.

Innovation Solution

A communication system that allows separate call forward destinations for each SIM-card identifier, with a network coordination function to forward calls to the correct voice mail or call forward destination based on the active line, even if the inactive line is busy or unreachable, using a roaming trombone elimination function for efficient call routing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a dual identifier system is implemented with one active identifier at a time, then the subscriber can have separate business and private lines with independent billing, but calls to the inactive line are incorrectly forwarded to the active line's voice mail instead of the inactive line's own voice mail

Engineering Contradiction:
Improveseparate voice mail functions for business and private linesVSAvoidcall forwarding accuracy
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The system segments the call forwarding function by maintaining separate voice mail destinations for each identifier (first and second identifiers). When a call is made to an inactive identifier, the network stores the called identifier information and forwards the call to that specific identifier's voice mail destination, rather than routing it through the active identifier's voice mail. This segmentation ensures that each line has its own independent voice mail function.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The network introduces an intermediary function that intercepts calls to inactive identifiers before they are incorrectly routed to the active identifier's voice mail. The network stores the identifier information of the called party and uses this information to determine the correct voice mail destination, acting as a mediator between the caller and the appropriate voice mail system.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If international roaming call forwarding is implemented, then calls can be forwarded to home network voice mail from visited networks, but unnecessary international legs are created increasing call costs

Engineering Contradiction:
Improvecall forwarding from visited network to home networkVSAvoidinternational roaming costs
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The system performs preliminary action by storing the home network voice mail destination information in advance. When a call is made to a mobile terminal on international roaming, the network uses the pre-stored destination information to directly route the call to the home network voice mail, avoiding the need to establish unnecessary international legs through the visited network first.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system extracts and eliminates the unnecessary international leg from the call path. Instead of routing calls through the visited network's voice mail system and then back to the home network, the solution directly connects the caller to the home network voice mail by removing the intermediate international routing step, thereby reducing call costs.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP2637429B1Call establishment to an active SIM card identifier in a mobile communications network
Publication Date: 2017.11.29 TELEFONICA GERMANY GMBH & CO
  • EP2637429B1 patent drawingFigure 1a
  • EP2637429B1 patent drawingFigure 1b
  • EP2637429B1 patent drawingFigure 1c

AI summary

This invention represents a communication system for providing mobile communication between a network and an mobile terminal, the mobile terminal being equipped with one or more SIM-cards, the one or more SIM-cards having at least a first and a second identifier, the mobile terminal and/or the network having an activation function for choosing one out of the identifiers as an active identifier, the network having a connecting function for establishing calls to the identifier that is active, wherein, if a call to the first identifier is requested while the second identifier is active, a call to the second identifier is established, wherein a first call forward destination is assigned to the first identifier and a second, separate call forward destination is assigned to the second identifier, wherein if a call to the first identifier is requested while the second identifier is active, such that a call to the second identifier is established, but the second identifier is not answering and/or busy and/or not reachable, a communication with the call forward destination of the first identifier is established by a coordination function of the network.