$re = '/^(?:[0187]?|\+[87]?)[- .]?(?:(\([2-9]\d{2}\)|[2-9]\d{2})[- .]?[- .]?(\d)[- .]?[- .]?(\d)[- .]?[- .]?(\d)[- .]?[- .]?(\d)[- .]?[- .]?(\d)[- .]?[- .]?(\d)[- .]?[- .]?(\d)[- .]?)$/m';
$str = '+89031231232
92912312-32
+7929 123 12 32
+8 929 12-312-32
+8 929 123-12-32';
$subst = "+7 (\1) \2\3\4 \5\6 \7\8";
$result = preg_replace($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