SS7 CNAM Query Analysis for Remote Call Forwarding Detection
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Solution Overview
Problem
Detention facility service providers face revenue loss and security compromise due to remote call forwarding services that arbitrage lower rates, leading to inaccurate call termination point visibility and security breaches.
Innovation Solution
Utilizing SS7 caller ID with name (CNAM) queries to detect remote call forwarding by populating a database with originating and terminating phone numbers, comparing query information to expected data, and taking call treatment actions such as releasing or blocking calls, or alerting personnel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If remote call forwarding is allowed to arbitrage lower rates, then service providers can offer lower calling rates to customers, but revenue is lost and security is compromised due to inaccurate call termination point visibility
Solution Approach 1:
The system implements feedback by monitoring SS7 CNAM queries from terminating switches and comparing the requesting phone number against the expected terminating number. When a mismatch is detected, the system provides feedback to block the call or alert personnel, preventing revenue loss and security breaches while allowing legitimate calls to proceed
Solution Approach 2:
The patent introduces an intermediary monitoring system that sits between the telephony network and the call routing process. This intermediary intercepts SS7 signaling messages, performs security checks by comparing phone numbers, and mediates call routing decisions without disrupting legitimate call flow, thus protecting revenue and security while maintaining service functionality
2Measurement precision
If call forwarding detection is implemented by monitoring SS7 signaling messages, then call termination point visibility is improved, but system complexity increases due to additional signaling interception and comparison mechanisms
Solution Approach 1:
The system leverages the existing SS7 signaling infrastructure and CNAM query mechanisms already present in the telephony network. By making the monitoring system multi-functional—using existing signaling paths for both legitimate call setup and security monitoring—it achieves precise call termination point visibility without requiring entirely new communication infrastructure, thus limiting complexity increases
3Reliability
If real-time comparison of phone numbers is performed to detect mismatches, then security response time is improved, but processing speed requirements increase
Solution Approach 1:
The system performs preliminary actions by pre-establishing the expected terminating number information before calls are placed. When SS7 CNAM queries arrive, the comparison against pre-stored expected numbers can be performed rapidly without requiring complex real-time analysis, thus achieving fast security response while maintaining call processing speed
Data Source
AI summary
Disclosed are systems and methods for using messages received from a remote switch to detect remote call forwarding. Embodiments utilize call intelligence associated with a database on an SS7 network to receive messages from a terminating switch. The return address of the message may be compared to an expected terminating switch address to confirm that the expected switch terminated the call. Embodiments may further compare a terminating phone number contained within the received message to an expected terminating phone number. Embodiments provide for various call handling in the event that a query is received from a switch other than the expected terminating switch. Such call handling may include terminating the call, recording the call, attempting to identify the called party, notifying proper authorities of the call, and/or the like. Embodiments of the invention may be deployed as part of a controlled environment facility service provider system, or in particular a detention facility service provider system.