Telecommunications System Blocking Spoofed Calls

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Solution Overview

Problem

Malicious actors are using easily available open-source software to spoof calls with minimal costs and effort, resulting in billions of spoofed calls per month, which are annoying to receivers and stress network resources.

Innovation Solution

A telecommunications system that uses a Spoofed Call Identification Function (SCIF) to assess the authenticity of inbound calls by comparing call attributes such as SIP identifiers, phone numbers, and IP addresses against pre-configured lists, and instructs a Session Border Controller (SBC) to block illegitimate calls.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If call spoofing is allowed on the network, then network capacity and resource utilization are improved, but network security and user experience deteriorate due to malicious spoofed calls

Engineering Contradiction:

Improvenetwork capacityVSAvoidnetwork security

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

A Session Border Controller (SBC) is introduced as an intermediary device at the network boundary to inspect and filter incoming calls. The SBC compares SIP identifiers and other call attributes against a database of legitimate customer information to block spoofed calls while allowing legitimate traffic to pass through, thus maintaining network capacity while improving security

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system implements feedback mechanisms where the SBC continuously monitors incoming calls, compares them against updated customer information databases, and dynamically adjusts call routing decisions. This feedback loop enables the network to adapt to new spoofing techniques while maintaining high throughput for legitimate calls

Inventive Principle:

Principle #23Feedback

2Ease of operation

If all inbound calls are allowed without verification, then ease of operation is improved, but measurement precision of call authenticity deteriorates

Engineering Contradiction:

Improvecall admissionVSAvoidcall authenticity verification

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

Customer information including SIP identifiers, phone numbers, and IP addresses is pre-configured in a database before calls arrive. The SBC performs preliminary verification by comparing incoming call attributes against this pre-configured information, enabling rapid authentication decisions without compromising ease of operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The call verification process is segmented into multiple independent checks: SIP identifier matching, phone number validation, IP address verification, and header field inspection. This segmentation allows the system to maintain high processing speed while improving authentication precision through multiple verification layers

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If call attributes are appended and verified for each inbound call, then call authenticity assessment is improved, but device complexity increases

Engineering Contradiction:

Improvecall authenticity assessmentVSAvoidverification system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The Session Border Controller is designed as a multi-functional device that simultaneously performs call routing, authentication, filtering, and monitoring functions. By consolidating multiple verification tasks into a single universal platform, the system improves assessment precision without proportionally increasing overall device complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

Instead of implementing complex verification logic in multiple distributed points, the system creates a centralized copy of customer information databases and verification rules at the SBC. This centralized copying approach simplifies the distributed system architecture while maintaining high authentication precision through consistent verification criteria

Inventive Principle:

Principle #26Copying

4Reliability

If spoofed calls are blocked using identifier matching, then network security is improved, but loss of legitimate calls may occur due to false rejections

Engineering Contradiction:

Improvenetwork securityVSAvoidlegitimate call throughput

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The SBC implements partial verification by checking multiple call attributes (SIP identifier, phone number, IP address, header fields) rather than relying on a single criterion. This multi-criteria approach reduces false rejections of legitimate calls while maintaining effective blocking of spoofed calls, balancing security with call throughput

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20250168274A1Telecommunications system for blocking spoofed calls

Publication Date: 2025.05.22 T MOBILE US INC

AI summary

A system of a telecommunications network that blocks spoofed calls. The system includes an interconnect session border controller (I-SBC) that can receive an inbound call over a network interface. The inbound call is associated with an identifier (e.g., a Session Initiation Protocol (SIP) identifier). The I-SBC causes a Spoofed Call Identification Function (SCIF) to compare the SIP identifier of the inbound call against a list of allowable SIP identifiers. In one example, the I-SBC receives an indication from the SCIF that the SIP identifier of the inbound call does not match any identifier on the list of allowable SIP identifiers. As such, the system rejects the inbound call as an illegitimate call. The illegitimate call is not forwarded to an IP Multimedia Subsystem (IMS) of the telecommunications network.