Radisys TTY T.140 Transcoding Overview
 

Radisys TTY T.140 Transcoding Overview

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Read how the Radisys scalable TTY/T.140 will provide transcoding support, essential for VoLTE and VOIP Service Providers, and will enable communication access for the hearing impaired. This ...

Read how the Radisys scalable TTY/T.140 will provide transcoding support, essential for VoLTE and VOIP Service Providers, and will enable communication access for the hearing impaired. This presentation outlines the various use cases that are supported by the Radisys MPX-12000.

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    Radisys TTY T.140 Transcoding Overview Radisys TTY T.140 Transcoding Overview Presentation Transcript

    • Radisys Transcoding TTY / T.140 Feature Overview September, 2013
    • Summary  Broadband and mobile network operators have a legal obligation to support communications access for the hearing impaired.  TTY/TDD is an old voice band modem still used by hearing impaired to communicate over telephone lines.  T.140 defines how TTY can be transmitted in an RTP media stream  Hence, TTY/T.140 transcoding support is essential for VoLTE and VoIP service providers  Radisys is introducing scalable TTY/T.140 transcoding on our MPX-12000 Broadband MRF in 1Q14. Radisys MPX-12000 Broadband MRF Radisys Corporation Confidential
    • TTY/TDD Overview  TTY/TDD is an old voice band modem still used by hearing impaired to communicate over telephone lines. • It consists of 45.45 bps 5 bit baudot codes which are FSK encoded according to ITU V.18, and TIA/EIA-825. • The 5 bit character set contains only the upper case alphabet but there is a shift key which is used to increase the character set to support numbers, symbols, and some special characters. Radisys Corporation Confidential
    • T.140 Overview Sample TTY/T.140 transcode call flow  T.140 defines how TTY can be transmitted in an RTP media stream  RFC 4103 defines a RTP payload format “text/t140” for transmitting T.140 text on an RTP session dedicated for the transmission of text, separate from the audio RTP stream. • RFC 4351 defines another RTP payload format “audio/t140c” for transmitting audio and text data within a single RTP session. This format is often used in PSTN gateway. This is NOT the format we’re going to support.  Sample call flow • Assumes RFC4117 is the control interface to invoke transcoding service • Assumes RTP payload format “text/t140” as per RFC 4103 is used to transmit T.140 text over RTP. Radisys Corporation Confidential
    • Use Cases Supported  Solution negotiates and support calls with TTY or T.140.  Supports transcoding via RFC 4117 between “text/t140” and following audio codecs: • G.711, G.722, G.729, AMR, AMR-WB  Use Cases Supported 1. UE1 (Txt/T.140) <-> UE2 (Txt/T.140) 2. UE1 (Txt/T.140) <-> UE2 (AMR-N/WB, G Series...) 3. UE1 (AMR-N/WB, G Series...) <-> UE2 (Txt/T.140) 4. UE1 (AMR-N/WB, G Series, Txt/T.140) <-> UE2 (Txt/T.140) 5. Txt/T.140 can be added / removed during any ongoing audio/video session via SDP negotiation 6. Audio/Video can be added / removed during any ongoing Txt/T.140 session via SDP negotiation  Supports enabling/disabling RTP redundancy (RFC2198) if needed  Supports video sessions with T.140/audio transcoding Radisys Corporation Confidential
    • System Design TTY <-> T.140 transcoding  high-level system design to support the transcoding service as described in Figure 1 (i.e.: one party supports audio+text, and the other party supports audio-only).  Note that a separate video RTP stream can also be added to each UE if they have video capability. Radisys Corporation Confidential
    • System Design T.140 <-> T.140 passthru  high-level minstrel design to support the T.140-T.140 passthrough scenario (i.e.: both parties support audio+text). Radisys Corporation Confidential
    • Radisys MRF Platform Support TTY/T.140 Transcoding  MPX-12000 (GA = 1Q14) • TTY/T.140 transcoding supported on MPC6 (high density DSP) blade • Implementation includes comprehensive hardware-level redundancy  Software MRF (GA = tbd) • TTY/T.140 transcoding support on SW MRF platforms will be prioritized on a business-driven basis Radisys Corporation Confidential