How to check the validity of the number in php?

Question

PHP

The number from the user is received in the format 7(999)999 99-99, how to filter numbers like:
7(000)000 00-00, 7(777)777 77-77, etc.?

Answer 1

You can check only the first couple of digits, everything else can be anything.
https://www.regextester.com/94215
So [phone] is a very real number, like [phone]
The maximum that can be done is to check for the same characters in the number, if at all the entire number consists of one digit, then draw conclusions.
In general, if you really need to validate a number, send an SMS to it or dial it with a random number (although it seems already illegal in the Russian Federation, you can’t replace numbers with any) and ask for numbers.

Answer 2

if(count( array_unique( str_split( preg_replace("/[^0-9]/", "", $_POST['tel']) ))) > 4) {
}