ENUM Bypass Flag for PSTN Call Routing

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Solution Overview

Problem

Existing IP telephony systems do not allow callers or ENUM subscribers to flexibly route calls through the Public Switched Telephone Network (PSTN) instead of the IP network, limiting options based on preferences such as privacy, quality of service, and equipment availability.

Innovation Solution

Implementing an ENUM bypass flag that allows callers or subscribers to prefer PSTN routing by skipping the default ENUM/DNS query, enabling calls to be carried via PSTN and terminated at a PSTN endpoint instead of an IP endpoint, based on preferences stored in a registration server.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If ENUM/DNS query is used for call routing, then IP telephony service is provided, but flexibility to route via PSTN is lost

Engineering Contradiction:

Improverouting flexibilityVSAvoidrouting system complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system dynamically switches between ENUM-based IP routing and PSTN routing based on real-time conditions such as network status, user preferences, and call requirements. The routing mechanism is no longer static but adapts to changing conditions, allowing the system to select the optimal path (IP or PSTN) for each call.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The routing system is designed to handle multiple functions: it can route calls via IP network using ENUM/DNS queries, switch to PSTN routing when needed, and support both VoIP and traditional telephony protocols. This multi-functional capability enables the system to serve diverse routing requirements through a single unified platform.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If call is routed via IP network, then VoIP service is delivered, but privacy and quality of service may be compromised

Engineering Contradiction:

Improvequality of serviceVSAvoidprivacy concerns

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The PSTN network serves as an intermediary routing option that mediates between the caller and callee when IP network routing is undesirable. By introducing PSTN as a middle layer, the system can bypass IP network concerns related to privacy and quality of service while still enabling call completion through traditional telephony infrastructure.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If ENUM bypass is implemented, then PSTN routing option is enabled, but additional routing logic is required

Engineering Contradiction:

Improverouting option flexibilityVSAvoidrouting logic complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system performs preliminary checks and decisions about routing preferences before actual call setup. User preferences, network conditions, and routing policies are evaluated in advance, and the appropriate routing path (ENUM or PSTN) is predetermined. This preliminary action simplifies the actual call routing process by avoiding complex real-time decisions during call establishment.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS7630485B2Method and system to bypass ENUM to reach a callee via a PSTN or a PLMN

Publication Date: 2009.12.08 SBC KNOWLEDGE VENTURES LP

AI summary

At least one telephone network element receives an attempt by a caller to place a telephone call to a telephone number of a callee. The telephone number is registered in a telephone number mapping (ENUM) database to receive incoming telephone calls via a Voice over Internet Protocol (VoIP) network. The at least one telephone network element determines a preference to carry the telephone call via a public switched telephone network (PSTN) or a public land mobile network (PLMN) instead of the VoIP network. Based on the preference, the telephone call is forwarded to a gateway to carry the telephone call to the callee via the PSTN or the PLMN instead of the VoIP network.