Voice-Grade Telecommunications Switch Data Delivery
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Solution Overview
Problem
Current methods for delivering call identifying information from an Intercept Access Point (IAP) switch to a law enforcement data collection system are costly and complex, relying on ISDN lines or private digital data circuits, which are not suitable for smaller agencies and do not meet emergency surveillance requirements.
Innovation Solution
The method employs Frequency Shift Keying (FSK) and Dual Tone Multi-Frequency (DTMF) signaling over voice-grade lines in the Public Switched Telephone Network (PSTN) to transmit call identifying information and enable two-way command and control communications, using existing switch hardware and analog delivery circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ISDN lines or private digital data circuits are used to deliver call identifying information, then data delivery capability is improved, but cost and device complexity increase significantly
Solution Approach 1:
The patent replaces expensive, complex ISDN lines and private digital data circuits with inexpensive, readily available voice-grade telephone lines. The system uses standard FSK modulation and DTMF signaling over public telephone network infrastructure, eliminating the need for costly dedicated data infrastructure while maintaining reliable data delivery capability for law enforcement surveillance.
Solution Approach 2:
The patent substitutes complex digital data circuit infrastructure with analog voice-grade telephone line infrastructure. By using FSK modulation to encode data over voice frequencies and DTMF signaling for control, the system replaces sophisticated digital switching infrastructure with simpler, well-established analog telephone network components.
2Reliability
If ISDN lines or private digital data circuits are used to deliver call identifying information, then data delivery capability is improved, but provisioning time and cost increase
Solution Approach 1:
The patent eliminates the need for time-consuming provisioning of dedicated ISDN lines or private data circuits by using pre-existing voice-grade telephone line infrastructure. Law enforcement agencies can immediately utilize the system through simple dial-up connections over the public telephone network, reducing provisioning lead time from weeks to minutes while maintaining reliable data delivery.
3Device complexity
If voice-grade lines are used for data delivery, then cost and complexity are reduced, but data transmission reliability may be compromised
Solution Approach 1:
The patent implements feedback mechanisms using DTMF signaling to enable two-way communication between the intercept access point and the data collection system. This allows for acknowledgment of received data, error detection, and retransmission requests, ensuring reliable data transmission over the voice-grade lines while maintaining system simplicity.
Solution Approach 2:
The patent modifies the voice-grade line parameters by using FSK modulation to encode data at specific frequencies (e.g., 1200 Hz for data, with variations for different data values). This parameter change enables reliable digital data transmission over analog voice infrastructure by utilizing the frequency discrimination capability of the telephone network while maintaining compatibility with existing voice-grade lines.
4Quantity of substance
If dedicated data circuits are provisioned, then data delivery capacity is sufficient, but the system becomes too complex for smaller law enforcement agencies
Solution Approach 1:
The patent makes the telephone network infrastructure universal by using the same voice-grade lines for both voice communication and data transmission. The FSK modulation allows data to be carried over existing telephone infrastructure that is already universally deployed, eliminating the need for separate dedicated data circuits and making the system accessible to agencies of all sizes without requiring complex infrastructure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces costs, simplifies provisioning, and provides faster and more flexible connections for law enforcement data delivery, allowing for real-time data transmission and error detection with retransmission capabilities, thus addressing the limitations of existing methods.
Implementation Method 1
The method employs Frequency Shift Keying (FSK) and Dual Tone Multi-Frequency (DTMF) signaling over voice-grade lines in the Public Switched Telephone Network (PSTN) to transmit call identifying information
Implementation Method 2
The method employs Frequency Shift Keying (FSK) and Dual Tone Multi-Frequency (DTMF) signaling over voice-grade lines in the Public Switched Telephone Network (PSTN) to transmit call identifying information and enable two-way command and control communications
Data Source
AI summary
Data generated at a telecommunications network switching node is selectively delivered to one or more data receiving device (e.g., data “collection box”) connected to the network, and command and control signaling is transmitted from the data receiving device to the switching node. This bi-directional communication is carried out in a manner compatible with voice grade lines. In an exemplary application, call identifying information, referred to in the TIA/EIA Standard as CDC (Call Data Channel) Messages, is delivered from an Intercept Access Point (IAP) switch that provides telephone service to a subject of an authorized surveillance order, to a law enforcement data collection box, utilizing Frequency Shift Keying (FSK) signals. Control signals are sent from the data collection box to the IAP switch utilizing Dual Tone Multi-Frequency (DTMF) signaling. The state of the art is advanced, and a contribution is made to law enforcement and other fields, as the invention allows replacement of costly and lengthily provisioned data delivery circuits, such as ISDN lines or private digital data circuits, with widely available and less expensive voice-band data delivery equipment.