VoIP Gateway Text Relay Mode for TTY Interoperability
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Solution Overview
Problem
Existing solutions for transporting Public Switched Telephone Network (PSTN) text phone signals over packet switched networks face challenges in interworking between dissimilar PSTN text phone modulations, leading to communication failures when gateways cannot support common modulation schemes, resulting in the inability to transition to text relay mode and maintain interoperability.
Innovation Solution
A communication scheme that allows VoIP devices to negotiate a transition to text relay mode, utilizing State Signaling Events (SSEs) to interwork dissimilar PSTN text terminal devices by identifying and translating PSTN modulation signals, even if they do not share a common set of modulations, enabling successful text calls between devices with different modulation schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If every PSTN text phone be supported by every gateway, then interoperability is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces text relay mode as an intermediary mechanism between dissimilar TTY devices. When gateways cannot directly support the same PSTN modulation, they use text relay mode over IP network as a mediator to translate between different modulation types, enabling interoperability without requiring every gateway to support every modulation directly
Solution Approach 2:
The patent segments the communication path into distinct modes: audio mode for direct modulation matching and text relay mode for protocol translation. This segmentation allows gateways to handle different modulation types through separate processing paths, reducing the complexity requirement for each individual gateway
2Adaptability or versatility
If a gateway shifts to text relay mode, then interoperability between dissimilar modulations is improved, but like PSTN text phone device interoperability may be sacrificed
Solution Approach 1:
The patent implements dynamic mode selection where gateways can switch between audio mode and text relay mode based on the capabilities of connected devices. The system dynamically determines whether to use direct audio transmission for like devices or text relay translation for dissimilar devices, optimizing performance for each scenario
Solution Approach 2:
The patent changes the operational parameters of the gateway by enabling it to operate in different modes (audio mode vs. text relay mode) depending on the modulation types detected. This parameter change allows the gateway to maintain reliability for like devices while achieving interoperability for dissimilar devices
3Adaptability or versatility
If text relay mode is used for dissimilar modulations, then communication between dissimilar PSTN text terminals is enabled, but communication failures occur when gateways cannot convert text back to PSTN modulation
Solution Approach 1:
The patent implements feedback mechanisms where gateways exchange capability information and negotiation messages to determine whether text relay mode is appropriate. The system uses feedback about supported modulations and device capabilities to make informed decisions about mode selection, preventing communication failures before they occur
Data Source
AI summary
A communication scheme allows two Voice Over Internet Protocol (VoIP) gateways that do not necessarily support a common set of Public Switched Telephone Network (PSTN) text terminal (TTY) modulations and which are communicating with dissimilar PSTN text terminal devices to negotiate a transition to text relay mode thus allowing those dissimilar PSTN text terminal devices to interwork with each other.