<!DOCTYPE html>
<html class="client-nojs vector-feature-night-mode-disabled vector-feature-language-in-header-enabled vector-feature-language-in-main-page-header-disabled vector-feature-page-tools-pinned-disabled vector-feature-toc-pinned-clientpref-1 vector-feature-main-menu-pinned-disabled vector-feature-limited-width-clientpref-1 vector-feature-limited-width-content-enabled vector-feature-custom-font-size-clientpref-1 vector-feature-appearance-pinned-clientpref-1 vector-sticky-header-enabled" lang="en" dir="ltr"><head>
<meta charset="UTF-8">
<title>User Data Header</title>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="canonical" href="https://en.wikipedia.org/wiki/User_Data_Header"> <link href="./mw/ext.cite.styles.css" rel="stylesheet" type="text/css">
<link href="./mw/skins.vector.icons.css" rel="stylesheet" type="text/css">
<link href="./mw/skins.vector.search.codex.styles.css" rel="stylesheet" type="text/css">
<link href="./mw/skins.vector.styles.css" rel="stylesheet" type="text/css">
<link href="./mw/user.styles.css" rel="stylesheet" type="text/css">
<meta name="ResourceLoaderDynamicStyles" content="">
<link rel="stylesheet" type="text/css" href="./mw/site.styles.css">
<link rel="stylesheet" type="text/css" href="./mw/noscript.css">
<link rel="stylesheet" type="text/css" href="./footer.css">
<link rel="stylesheet" type="text/css" href="./vector-2022.css">
</head>
<body class="skin--responsive skin-vector skin-vector-search-vue mediawiki ltr sitedir-ltr mw-hide-empty-elt ns-0 ns-subject page-User_Data_Header rootpage-User_Data_Header skin-vector-2022 action-view">
<div class="mw-page-container">
<div class="mw-page-container-inner">
<div class="mw-content-container">
<main id="content" class="mw-body">
<header class="mw-body-header vector-page-titlebar">
<h1 id="firstHeading" class="firstHeading mw-first-heading">
<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">User Data Header</span></span>
</h1>
</header>
<a id="top"></a>
<div id="bodyContent" class="vector-body ve-init-mw-desktopArticleTarget-targetContainer" aria-labelledby="firstHeading" data-mw-ve-target-container="">
<div id="mw-content-text" class="mw-body-content mw-content-ltr" lang="en" dir="ltr"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><p><b>User Data Header</b> (<b>UDH</b>) is a <a href="Binary_file" title="Binary file">binary</a> structure which may be present at the start of a short message in the <a href="Short_Message_Service" class="mw-redirect" title="Short Message Service">Short Message Service</a> in <a href="GSM" title="GSM">GSM</a>. It does not contain any text, but it specifies how the message should be formatted and processed.
</p><p>UDH can be used to form <a href="Concatenated_SMS" title="Concatenated SMS">Concatenated SMS</a>, to <a href="Enriched_text" title="Enriched text">enrich</a> the content of the message with colors, text formatting, small pictures and animations and simple music which are used in <a href="Enhanced_Messaging_Service" title="Enhanced Messaging Service">Enhanced Messaging Service</a> (EMS), to convey port numbers which may cause start of an application in the mobile phone, which is used for <a href="Multimedia_Messaging_Service" title="Multimedia Messaging Service">Multimedia Messaging Service</a> (MMS) or to indicate using of <a href="GSM_03.38#National_language_shift_tables" title="GSM 03.38">national language shift tables</a>.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>
</p><p>UDH is defined in <a href="GSM_03.40" title="GSM 03.40">3GPP 23.040 (originally GSM 03.40)</a>.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>
</p>
<meta property="mw:PageProp/toc">
<div class="mw-heading mw-heading2"><h2 id="Technical_Realization">Technical Realization</h2></div>
<p>Presence of User Data Header is indicated by the TP-UDHI (Transfer Layer Protocol User Data Header Indicator) bit - 6th bit of the first octet of the <a href="GSM_03.40" title="GSM 03.40">GSM 03.40 or 3GPP 23.040</a> message.
</p><p>If UDH is present, it is at the beginning of the TP-UD (TP-User Data) field and it always starts with an UDHL (UDH Length) octet. The rest of UDH is a sequence of Tag-Length-Value triplets. The Tag is named Information-Element-Identifier (IEI) and is always 1 octet long, the Length field is always 1 octet long and it specifies the length of the Information Element Data.
</p><p>UDH uses space intended for the message payload. The longer the UDH, the less space remains for the message text or other contents. When TP-UD contains seven-bit data, the length of TP-UD is given in septets (but UDHL is still in octets, so length in septets is (UDHL + 1) * 8 / 7) and the UDH is filled to a septet boundary with 0-6 zero bits. The next table shows how a TP-UD of a message in the GSM 7 bit default alphabet containing text 'Hi' with a predefined sound 'Chord high' will be encoded:
</p>
<table class="wikitable">
<tbody><tr>
<th>TP-UD Octet</th>
<th>1</th>
<th>2</th>
<th>3</th>
<th>4</th>
<th>5</th>
<th>6</th>
<th>7
</th></tr>
<tr>
<td>Value (hex)</td>
<td>04</td>
<td>0B</td>
<td>02</td>
<td>00</td>
<td>08</td>
<td>20</td>
<td>D3
</td></tr>
<tr>
<td>Meaning</td>
<td>UDH Length</td>
<td>IEI: Predefined sound</td>
<td>IE Length</td>
<td>Position</td>
<td>Chord high</td>
<td>6 lower bits of the 1st char + 2 fill bits</td>
<td>7 lower bits of the 2nd char + 1 upper bit of the first char
</td></tr></tbody></table>
<p>The total message length TP-UDL will be 8. (UDH has 8 * (1 + 4) = 40 bits, 2 bits is the padding as (40 + 2) / 7 = 6 without remainder, 2 * 7 = 14 bits for text; total TP-UD length is 40 + 2 + 14 = 56 bits = 7 octets = 8 septets.)
</p>
<div class="mw-heading mw-heading2"><h2 id="UDH_Information_Elements">UDH Information Elements</h2></div>
<table class="wikitable">
<tbody><tr>
<th>IEI (hex)</th>
<th>Meaning</th>
<th>Classification</th>
<th>Length</th>
<th>May repeat
</th></tr>
<tr>
<td>00</td>
<td><a href="Concatenated_SMS" title="Concatenated SMS">Concatenated short messages</a>, 8-bit reference number</td>
<td>SMS Control</td>
<td>3</td>
<td>no
</td></tr>
<tr>
<td>01</td>
<td>Special SMS Message Indication</td>
<td>SMS Control</td>
<td>2</td>
<td>yes
</td></tr>
<tr>
<td>02</td>
<td>Reserved</td>
<td>N/A</td>
<td>N/A</td>
<td>yes
</td></tr>
<tr>
<td>03</td>
<td>Not used to avoid misinterpretation as <LF> character</td>
<td>N/A</td>
<td>N/A</td>
<td>yes
</td></tr>
<tr>
<td>04</td>
<td><a href="Smart_Messaging" title="Smart Messaging">Application port addressing scheme</a>, 8 bit address</td>
<td>SMS Control</td>
<td>2</td>
<td>no
</td></tr>
<tr>
<td>05</td>
<td><a href="Smart_Messaging" title="Smart Messaging">Application port addressing scheme</a>, 16 bit address</td>
<td>SMS Control</td>
<td>4</td>
<td>no
</td></tr>
<tr>
<td>06</td>
<td>SMSC Control Parameters</td>
<td>SMS Control</td>
<td>1</td>
<td>no
</td></tr>
<tr>
<td>07</td>
<td>UDH Source Indicator</td>
<td>SMS Control</td>
<td>1</td>
<td>yes
</td></tr>
<tr>
<td>08</td>
<td><a href="Concatenated_SMS" title="Concatenated SMS">Concatenated short message</a>, 16-bit reference number</td>
<td>SMS Control</td>
<td>4</td>
<td>no
</td></tr>
<tr>
<td>09</td>
<td><a href="Wireless_Application_Protocol" title="Wireless Application Protocol">Wireless Control Message Protocol</a></td>
<td>SMS Control</td>
<td>1-255</td>
<td>yes
</td></tr>
<tr>
<td>0A</td>
<td>Text Formatting</td>
<td>EMS Control</td>
<td>3-4</td>
<td>yes
</td></tr>
<tr>
<td>0B</td>
<td>Predefined Sound</td>
<td>EMS Content</td>
<td>2</td>
<td>yes
</td></tr>
<tr>
<td>0C</td>
<td>User Defined Sound (<a href="IMelody" title="IMelody">iMelody</a> max 128 bytes)</td>
<td>EMS Content</td>
<td>2-129</td>
<td>yes
</td></tr>
<tr>
<td>0D</td>
<td>Predefined Animation</td>
<td>EMS Content</td>
<td>2</td>
<td>yes
</td></tr>
<tr>
<td>0E</td>
<td>Large Animation (16*16 times 4 = 32*4 =128 bytes)</td>
<td>EMS Content</td>
<td>129</td>
<td>yes
</td></tr>
<tr>
<td>0F</td>
<td>Small Animation (8*8 times 4 = 8*4 =32 bytes)</td>
<td>EMS Content</td>
<td>33</td>
<td>yes
</td></tr>
<tr>
<td>10</td>
<td>Large Picture (32*32 = 128 bytes)</td>
<td>EMS Content</td>
<td>129</td>
<td>yes
</td></tr>
<tr>
<td>11</td>
<td>Small Picture (16*16 = 32 bytes)</td>
<td>EMS Content</td>
<td>33</td>
<td>yes
</td></tr>
<tr>
<td>12</td>
<td>Variable Picture</td>
<td>EMS Content</td>
<td>4-255</td>
<td>yes
</td></tr>
<tr>
<td>13</td>
<td>User prompt indicator</td>
<td>EMS Control</td>
<td>1</td>
<td>yes
</td></tr>
<tr>
<td>14</td>
<td>Extended Object</td>
<td>EMS Content</td>
<td>7-255</td>
<td>yes
</td></tr>
<tr>
<td>15</td>
<td>Reused Extended Object</td>
<td>EMS Control</td>
<td>3</td>
<td>yes
</td></tr>
<tr>
<td>16</td>
<td>Compression Control</td>
<td>EMS Control</td>
<td>3-255</td>
<td>no
</td></tr>
<tr>
<td>17</td>
<td>Object Distribution Indicator</td>
<td>EMS Control</td>
<td>2</td>
<td>yes
</td></tr>
<tr>
<td>18</td>
<td>Standard WVG object</td>
<td>EMS Content</td>
<td>1-255</td>
<td>yes
</td></tr>
<tr>
<td>19</td>
<td>Character Size WVG object</td>
<td>EMS Content</td>
<td>1-255</td>
<td>yes
</td></tr>
<tr>
<td>1A</td>
<td>Extended Object Data Request Command</td>
<td>EMS Control</td>
<td>0-255</td>
<td>no
</td></tr>
<tr>
<td>1B</td>
<td>Reserved for future EMS features</td>
<td>N/A</td>
<td>0-255</td>
<td>yes
</td></tr>
<tr>
<td>1C</td>
<td>Reserved for future EMS features</td>
<td>N/A</td>
<td>0-255</td>
<td>yes
</td></tr>
<tr>
<td>1D</td>
<td>Reserved for future EMS features</td>
<td>N/A</td>
<td>0-255</td>
<td>yes
</td></tr>
<tr>
<td>1E</td>
<td>Reserved for future EMS features</td>
<td>N/A</td>
<td>0-255</td>
<td>yes
</td></tr>
<tr>
<td>1F</td>
<td>Reserved for future EMS features</td>
<td>N/A</td>
<td>0-255</td>
<td>yes
</td></tr>
<tr>
<td>20</td>
<td>RFC 822 E-Mail Header</td>
<td>SMS Control</td>
<td>1</td>
<td>no
</td></tr>
<tr>
<td>21</td>
<td>Hyperlink format element</td>
<td>SMS Control</td>
<td>0-255</td>
<td>yes
</td></tr>
<tr>
<td>22</td>
<td>Reply Address Element</td>
<td>SMS Control</td>
<td>1-255</td>
<td>no
</td></tr>
<tr>
<td>23</td>
<td>Enhanced Voice Mail Information</td>
<td>SMS Control</td>
<td>0-255</td>
<td>no
</td></tr>
<tr>
<td>24</td>
<td>National Language Single Shift</td>
<td>SMS Control</td>
<td>1</td>
<td>no
</td></tr>
<tr>
<td>25</td>
<td>National Language Locking Shift</td>
<td>SMS Control</td>
<td>1</td>
<td>no
</td></tr>
<tr>
<td>26
</td>
<td>Filler
</td>
<td>SMS Control
</td>
<td>0-255
</td>
<td>yes
</td></tr>
<tr>
<td>27 – 6F</td>
<td>Reserved for future use</td>
<td>N/A</td>
<td>0-255</td>
<td>N/A
</td></tr>
<tr>
<td>70 – 7F</td>
<td>(U)SIM Toolkit Security Headers</td>
<td>SMS Control</td>
<td>0-255</td>
<td>?
</td></tr>
<tr>
<td>80 – 9F</td>
<td>SME to SME specific use</td>
<td>SMS Control</td>
<td>0-255</td>
<td>?
</td></tr>
<tr>
<td>A0 – BF</td>
<td>Reserved for future use</td>
<td>N/A</td>
<td>0-255</td>
<td>?
</td></tr>
<tr>
<td>C0 – DF</td>
<td>SC specific use</td>
<td>SMS Control</td>
<td>0-255</td>
<td>?
</td></tr>
<tr>
<td>E0 – FF</td>
<td>Reserved for future use</td>
<td>N/A</td>
<td>0-255</td>
<td>?
</td></tr></tbody></table>
<div class="mw-heading mw-heading2"><h2 id="Use_in_Other_Protocols">Use in Other Protocols</h2></div>
<p>The UDH is used in other protocols for short message transport - <a href="Short_Message_Peer-to-Peer" title="Short Message Peer-to-Peer">Short Message Peer-to-Peer</a> (SMPP), <a href="Universal_Computer_Protocol" class="mw-redirect" title="Universal Computer Protocol">Universal Computer Protocol</a> (UCP) and in WEMT <a href="Teleservice" title="Teleservice">teleservice</a> in <a href="CDMA2000" title="CDMA2000">CDMA2000</a>.
</p>
<div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2></div>
<ul><li><a href="Short_Message_Service" class="mw-redirect" title="Short Message Service">Short Message Service</a></li>
<li><a href="GSM_03.38" title="GSM 03.38">GSM 03.38</a></li>
<li><a href="Enhanced_Messaging_Service" title="Enhanced Messaging Service">Enhanced Messaging Service</a></li>
<li><a href="Multimedia_Messaging_Service" title="Multimedia Messaging Service">Multimedia Messaging Service</a></li>
<li><a href="Short_Message_Peer-to-Peer" title="Short Message Peer-to-Peer">Short Message Peer-to-Peer</a></li>
<li><a href="Universal_Computer_Protocol" class="mw-redirect" title="Universal Computer Protocol">Universal Computer Protocol</a></li></ul>
<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>
<div class="mw-references-wrap"><ol class="references">
<li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><style data-mw-deduplicate="TemplateStyles:r1238218222">
/* start https://en.wikipedia.org/ */
.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("./mw/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("./mw/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("./mw/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("./mw/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}
/* end https://en.wikipedia.org/ */
</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=745">"Alphabets and language-specific information"</a>. <i>portal.3gpp.org</i><span class="reference-accessdate">. Retrieved <span class="nowrap">2021-07-19</span></span>.</cite></span>
</li>
<li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.3gpp.org/ftp/Specs/html-info/23040.htm">3rd Generation Partnership Project; Technical realization of the Short Message Service (SMS)</a></span>
</li>
</ol></div></div><!--htdig_noindex--><div><div class="zim-footer">
This article is issued from <a class="external text" title="Last edited on 2023-11-14" href="https://en.wikipedia.org/wiki/?title=User_Data_Header&oldid=1185125380">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.
</div>
</div><!--/htdig_noindex--></div>
</div>
</main>
</div>
</div>
</div>
</body></html>