$re = '/(([0-9.]+)\-)+([0-9]+)/u';
$str = '8-4-1-2-5
8 (8122) 56-56-56
8-911-1234567
8-495-1-234-zzz
8-911 12 345 67
8 (409) 123-123-123
1-2-3-4-5-6-8-7-6';
$subst = "";
$result = preg_replace($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