<?php
 
error_reporting(-1);
$regexp= "/^\\s*(8|([+]\\W*7))(\\W*\d){10}$/ui";
 
$numbers = [ // Правильные:
  '84951234567',  '+74951234567', '8-495-1-234-567', 
  ' 8 (8122) 56-56-56', '8-911-1234567', '8 (911) 12 345 67', 
  '8-911 12 345 67', '8 (911) - 123 - 45 - 67', '+ 7 999 123 4567', 
  '8 ( 999 ) 1234567', '8 999 123 4567',
// Неправильные: 
  '02', '84951234567 позвать люсю', '849512345', '849512345678', 
  '8 (409) 123-123-123', '7900123467', '5005005001', '8888-8888-88',
  '84951a234567', '8495123456a', 
  '+1 234 5678901', /* неверный код страны */
  '+8 234 5678901', /* либо 8 либо +7 */
  '7 234 5678901' /* нет + */
];
foreach ($numbers as $number)
{
	if (preg_match($regexp, $number))
	{
		echo "{$number} - верный номер\n";	
	}
	else 
	{
		echo "{$number} - неверный номер\n";
	}
}

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