<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
        {font-family:"Cambria Math";
        panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
        {font-family:Calibri;
        panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
        {margin:0cm;
        margin-bottom:.0001pt;
        font-size:11.0pt;
        font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
        {mso-style-priority:99;
        color:#0563C1;
        text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
        {mso-style-priority:99;
        color:#954F72;
        text-decoration:underline;}
span.EmailStyle17
        {mso-style-type:personal-compose;
        font-family:"Calibri",sans-serif;
        color:windowtext;}
.MsoChpDefault
        {mso-style-type:export-only;}
@page WordSection1
        {size:612.0pt 792.0pt;
        margin:70.85pt 70.85pt 70.85pt 70.85pt;}
div.WordSection1
        {page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="#0563C1" vlink="#954F72">
<div class="WordSection1">
<p class="MsoNormal">I&#8217;m using switch_channel_get_variable to extract sip headers with already predefined channel variables (https://freeswitch.org/confluence/display/FREESWITCH/Channel&#43;Variables).<o:p></o:p></p>
<p class="MsoNormal">I&#8217;ve found that some undefined sip headers can be extracted using only &#8216;sip_&#8217; prefix (for instance &#8216;sip_P-Preferred-Identity&#8217;) and some using &#8216;sip_h_&#8217; prefix (like is &#8216;sip_h_Diversion&#8217;).<o:p></o:p></p>
<p class="MsoNormal">Is there some rule or detailed explanation when to use just &#8216;sip_&#8217; or &#8216;sip_h_&#8217; in the name of the required channel variable?<o:p></o:p></p>
<p class="MsoNormal"><o:p>&nbsp;</o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Miro<o:p></o:p></p>
</div>
</body>
</html>