<?php

error_reporting(-1);

$correctNumbers = [ 
  '84951234567',  '+74951234567', '8-495-1-234-567', 
  ' 8 (8122) 56-56-56', '8-911-1234567', '8 (911) 12 345 67', 
  '8-911 12 345 67', '8 (911) - 123 - 45 - 67', '+ 7 999 123 4567', 
  '8 ( 999 ) 1234567', '8 999 123 4567'
];

$regexp1 = '/[ ()-]*/';
$regexp2 = '/[+]7/';

foreach ($correctNumbers as $phoneNumber) {
	$typicalPhoneNumber = preg_replace($regexp1, "", $phoneNumber);
	$typicalPhoneNumber = preg_replace($regexp2, '8', $typicalPhoneNumber);
	echo "{$phoneNumber} - {$typicalPhoneNumber}\n";
};