$re = '/^\s*(\+[0-9][0-9]\s*|0|)(7.*)/mix';
$str = '+41 79 123 456 78
+417612345678
076 123 456 78
07812345678
7712345678
+41 47 123 456 78
+413212345678
021 123 456 78
02212345678
3412345678';
$subst = "$2";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php