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    <div class="moz-cite-prefix">Op 09/07/2012 11:40, Mark Rejhon
      schreef:<br>
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cite="mid:CAA79oDkR0fsSwtHP27yhswdmncgmVpNYodi6RjTswpuByBgS+A@mail.gmail.com"
      type="cite">
      <div class="gmail_quote">On Mon, Jul 9, 2012 at 2:09 AM, Edward
        Tie <span dir="ltr"><<a moz-do-not-send="true"
            href="mailto:famtie@xs4all.nl" target="_blank">famtie@xs4all.nl</a>></span>
        wrote:<br>
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          <div bgcolor="#FFFFFF" text="#000000"> Hi Mark,<br>
                 I want to add on history of textphone and XMPP to old
            telephones that uses older protocols:<br>
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        <div><br>
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        <div>Hello Edward,
          <div>Good history -- however, this is already beyond scope of
            XEP-0301.</div>
          <div>Anybody can create an XEP-0301 gateway that converts to
            almost anything (including any of the protocols you
            mention). </div>
          <div><br>
          </div>
          <div>One sentence will be added to satisfy this.</div>
          <div><a moz-do-not-send="true"
href="http://xmpp.org/extensions/xep-0301.html#interoperability_considerations">http://xmpp.org/extensions/xep-0301.html#interoperability_considerations</a> </div>
          <div>To just simply mention that "...a gateway can be built as
            a part of a complete solution (i.e. with optional audio,
            such as to support Voice Carry Over) to support any legacy
            protocols used by TTY and textphones using various protocols
            including Baudot, 300 baud ASCII, DTMF, ITU-T V.18, ITU-T
            V.22, and other text transmission protocols". (wording will
            be refined upon consultation within R3TF including Gregg
            Vanderheiden who helps out in this area)</div>
          <div><br>
          </div>
          <div>There was a lot of debate within our group (i.e. Gregg
            Vanderheiden) about the careful choice of wording, because
            we need to be sensitive about the "complete solution" (such
            as worldwide interoperability, the ability to use voice,
            accessibility to people who don't have Internet, etc).</div>
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    <br>
    it's now a clear history :-) <br>
    <br>
    <br>
    <br>
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cite="mid:CAA79oDkR0fsSwtHP27yhswdmncgmVpNYodi6RjTswpuByBgS+A@mail.gmail.com"
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        <div> </div>
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            <h2><span>Protocols</span></h2>
            <p>There are many different textphone standards.</p>
            <h3> <span>Baudot code</span></h3>
            <p>The original standard used by TTYs is the <a
                moz-do-not-send="true"
                href="http://en.wikipedia.org/wiki/Baudot_code"
                title="Baudot code" target="_blank">Baudot code</a>
              implemented asynchronously at either 45.5 or 50 baud, 1
              start bit, 5 data bits, and 1.5 stop bits. Baudot is a
              common protocol in the US.</p>
            <h3> <span>Turbo Code</span></h3>
            <p>In addition to regular Baudot, the <a
                moz-do-not-send="true"
href="http://en.wikipedia.org/w/index.php?title=UltraTec&action=edit&redlink=1"
                title="UltraTec (page does not exist)" target="_blank">UltraTec</a>
              company implements another protocol known as Enhanced TTY,
              which it calls "Turbo Code," in its products. Turbo Code
              has some advantages over Baudot protocols, such as a
              higher data rate, full <a moz-do-not-send="true"
                href="http://en.wikipedia.org/wiki/ASCII" title="ASCII"
                target="_blank">ASCII</a> compliance, and full-duplex
              capability. However, Turbo Code is proprietary, and
              UltraTec only gives its specifications to parties who are
              willing to license it.</p>
            <h3> <span>Other legacy protocols</span></h3>
            <p>Other protocols used for text telephony are European Deaf
              Telephone (EDT) and <a moz-do-not-send="true"
                href="http://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling"
                title="Dual-tone multi-frequency signaling"
                target="_blank">Dual-tone multi-frequency signaling</a>
              (DTMF).</p>
            <p>The ITU V series recommendations are a collection of
              early modem standards approved by the <a
                moz-do-not-send="true"
                href="http://en.wikipedia.org/wiki/ITU" title="ITU"
                target="_blank">ITU</a> in 1988.</p>
            <ul>
              <li><a moz-do-not-send="true"
                  href="http://en.wikipedia.org/wiki/ITU_V.21"
                  title="ITU V.21" target="_blank">ITU V.21</a> <a
                  moz-do-not-send="true" rel="nofollow"
href="http://www.itu.int/rec/T-REC-V.21/recommendation.asp?lang=en&parent=T-REC-V.21-198811-I"
                  target="_blank">[1]</a> specifies 300 bits per second
                duplex mode.</li>
              <li><a moz-do-not-send="true"
                  href="http://en.wikipedia.org/wiki/ITU_V.23"
                  title="ITU V.23" target="_blank">ITU V.23</a> <a
                  moz-do-not-send="true" rel="nofollow"
href="http://www.itu.int/rec/T-REC-V/recommendation.asp?lang=en&parent=T-REC-V.23"
                  target="_blank">[2]</a> specifies <a
                  moz-do-not-send="true"
                  href="http://en.wikipedia.org/wiki/Audio_frequency-shift_keying"
                  title="Audio frequency-shift keying" target="_blank">audio

                  frequency-shift keying</a> modulation to encode and
                transfer data at 600/1200 bits per second.</li>
            </ul>
            <h3> <span>V.18</span></h3>
            <p>In 1994 the <a moz-do-not-send="true"
href="http://en.wikipedia.org/wiki/International_Telecommunication_Union"
                title="International Telecommunication Union"
                target="_blank">ITU</a> approved the <a
                moz-do-not-send="true"
href="http://en.wikipedia.org/w/index.php?title=ITU_V.18&action=edit&redlink=1"
                title="ITU V.18 (page does not exist)" target="_blank">V.18</a>
              standard <a moz-do-not-send="true" rel="nofollow"
                href="http://www.itu.int/rec/T-REC-V.18/en"
                target="_blank">[3]</a>. V.18 is a dual standard. It is
              both an umbrella protocol that allows recognition and
              interoperability of some of the most commonly used
              textphone protocols, as well as offering a native V.18
              mode, which is an <a moz-do-not-send="true"
                href="http://en.wikipedia.org/wiki/ASCII" title="ASCII"
                target="_blank">ASCII</a> full- or half-duplex
              modulation method.</p>
            <p>Computers can, with appropriate software and modem,
              emulate a V.18 TTY. Some voice modems, coupled with
              appropriate software, can now be converted to TTY modems
              by using a software-based decoder for TTY tones. Same can
              be done with such software using a computer's sound card,
              when coupled to the telephone line.</p>
            <p>In the UK, a virtual V.18 network, called TextDirect,
              exists as part of the <a moz-do-not-send="true"
                href="http://en.wikipedia.org/wiki/Public_Switched_Telephone_Network"
                title="Public Switched Telephone Network"
                target="_blank">Public Switched Telephone Network</a>,
              thereby offering interoperability between textphones using
              different protocols. The platform also offers additional
              functionality like call progress and status information in
              text and automatic invocation of a relay service for
              speech-to-text calls.</p>
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