How do i use a substring

Hello everybody,

I have a telephone number

1234567890ABCD
which i recieve from an XML BatchResponse, i use an XML Schema

i want to seperate it in my XSL as

123-456-7890-ABCD

So any clues how to do it?
<xsl:for-each select="attr[@name='telephoneNumber']">
  <xsl:value-of select="substring(value, 1, 3)"></xsl:value-of>
</xsl:for-each>

The substring function does'nt work here
again the same

<xsl:stylesheet xmlns:xsl="http://www.w3.org/TR/WD-xsl">
namespace problem i guess,

i have installed the MSXML3 in replace mode from netcrucible.com
but still it does'nt recognize the substring function.


Regards,
Suman

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