Jos,
I tried both ways and they are not working, besides I also removed a $ in the string from M23.
here are the both:
#include <File.au3>
AutoItSetOption("ExpandVarStrings", 1)
$valuefile = @UserName
$result = StringRegExp(FileRead("C:\tmp\Test.txt"),$valuefile & "\s=\s(.*)", 1)
MsgBox(0, "", $result[0])
_FileWriteToLine("Q:\test\assi.config", 102, ' <setting name="PhoneInterfaceServiceProvider">$result$ (Aastra2380ip)</setting>', True)
and
#include <File.au3>
AutoItSetOption("ExpandVarStrings", 1)
$valuefile = @UserName
$result = StringRegExp(FileRead("C:\tmp\Test.txt"),$valuefile & "\s=\s(.*)", 1)
MsgBox(0, "", $result[0])
_FileWriteToLine("Q:\test\assi.config", 102, ' <setting name="PhoneInterfaceServiceProvider">' & $result & ' (Aastra2380ip)</setting>', True)