<?xml version="1.0" encoding="utf-8" standalone="yes"?><html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>GSM System Security</title>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type" />
<meta content="text/css" http-equiv="Content-Style-Type" />
<script src="NED?action=retrieve&amp;identifier=dn00188761&amp;edition=1&amp;language=none&amp;coverage=global&amp;encoding=javascript&amp;component=data&amp;item=data" type="text/javascript" xml:space="preserve">
</script>
<?conversion name="Pub2XHTML" version="2.0" source="urn:mars:dn02229403:2:en:global:publishing_online_1_0:data:data:*:*:*" date="2005-02-28T16:25:10Z"?>
<link href="NED?action=retrieve&amp;identifier=dn01158124&amp;edition=1&amp;language=en&amp;coverage=global&amp;encoding=css&amp;component=data&amp;item=data" rel="stylesheet" title="Nokia Networks default online style" type="text/css" />
<meta content="draft" name="status" />
<?conversion name="SplitHTML" version="1.9" source="urn:mars:dn02229403:2:en:global:publishing_online_1_0:data:data:14:*:*" date="2005-02-28T16:25:10Z"?>
</head>
<body lang="en" xml:lang="en">
<p><a name="ned_top" shape="rect"></a>
<a name="ned_1" shape="rect"></a></p>

<a name="dec331440551" shape="rect"></a>
<a name="p2xhtm-repid-1" shape="rect"></a>
<table width="100%">
<tr>
<td align="center" colspan="1" rowspan="1" width="20%"><?NED5 annotation?>
<br clear="none" /><?NED5 printview?>
</td>
<td align="center" colspan="1" rowspan="1" width="20%"></td>
<td align="center" colspan="1" rowspan="1" width="20%"></td>
<td align="center" colspan="1" rowspan="1" width="20%"></td>
<td align="center" colspan="1" rowspan="1" width="20%"><a href="NED?action=retrieve&amp;identifier=dn02229403_about&amp;edition=2&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=ned_top#ned_top" onclick="openSmallPopup(event,'NED?action=retrieve&amp;identifier=dn02229403_about&amp;edition=2&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=ned_top#ned_top');return false" shape="rect" target="_blank"><img alt="Document information" border="0" class="Metainfo" src="NED?action=retrieve&amp;identifier=dn01158003&amp;edition=1&amp;language=en&amp;coverage=global&amp;encoding=gif&amp;component=data&amp;item=data" /></a></td>
</tr>
</table>


<div class="div">
<h1>GSM System Security</h1>

<p>In the GSM system much attention has been paid to the security
and call privacy. Both the speech and equipment are secured against misuse
as stated in the GSM specifications.</p>


<a name="p2xhtm-repid-2" shape="rect"></a>
<div class="div">
<h2>Call security</h2>

<p>Ciphering is one of the security procedures designed to
protect the subscriber's identity and data. It is an optional procedure in
GSM. When the ciphering is active, all information exchanged between the mobile
and the network on the dedicated radio channels is encrypted. A key previously
set between the network and the mobile station (MS) is used to encipher and
to decipher the encrypted information. The encryption algorithms applied to
a GSM network are extremely sophisticated and make it virtually impossible
to break the code.</p>


<p>Nokia Transcoder Submultiplexer (TCSM) performs speech
coding according to the speech compression methods mentioned in the GSM specifications.
It restricts tapping into the radio network. The GSM system also applies temporary
caller identities in the course of a call, which makes it impossible for an
outsider to trace the call.</p>
</div>


<p><a href="NED?action=retrieve&amp;identifier=dn02229403&amp;edition=2&amp;language=en&amp;coverage=global&amp;encoding=xhtml_1_0&amp;component=data&amp;item=data&amp;pointer=ned_2#ned_2" onclick="sync(this);return true" shape="rect">Operation and Maintenance security</a></p>
</div>
</body>
</html>