looking to validate US phone number w/ area code - php

Question

I'm working on a function to validate a US phone number submitted by a user, which can be submitted in any of the popular number formats people usually use. My code so far is as follows:
$number = '123-456-7890';
function validate_telephone_number($number) {
$formats = array(
'###-###-####',
'(###)###-###',
'(###) ###-###',
'##########'
);
$number = trim(preg_replace('[0-9]', '#', $number));
if (in_array($number, $formats)) {
return true;
} else {
return false;
}
}
First off, this code does not seem to be working, and returns false on all submitted numbers. I can't seem to find my error.
Secondly, I'm looking for an easy way to only allow phone numbers from an array of specific allowed area codes. Any ideas?

Answer 1

For your first question:
preg_replace('/[0-9]/', '#', $number)
or '/\d/'
For the second question this may help you:
$areaCode = substr(preg_replace('/[^\d]/', '', $number),0 , 3);
This will give you the first 3 digits in the number by discarding all other characters.
I'm not familiar with the US area codes format so I cannot help you more with this one.
Bonus:
if (in_array($number, $formats)) {
return true;
} else {
return false;
}
is equivalent to
return in_array($number, $formats);
As a matter of fact any statement of the form
if(<expression>){
return true;
}
else{
return false;
}
can be written as return (bool) <expr>;, but in this case in_array will always return a Boolean so (bool) is not needed.

Answer 2

Your code does not check for well formatted but invalid numbers - for example, no area code starts with 0 or 1 in the US, so this could be checked. Also, your formats do not allow for country code inclusion - [phone] would be rejected, for example.
If you don't care about the formatting and just want to validate if the digits in the input amount to a valid US phone number, you could use something like this:
$clean_number = preg_replace("/[^0-9]/", '', $number);
$valid = preg_match("/^(\+?1)?[2-9][0-9]{9}$/", $clean_number);
Of course, this will also accept "foo 5555555555 bar" as a valid number - if you want to disallow that, make the preg_replace more restrictive (e.g, remove only brackets, spaces and dashes).

Answer 3

If you prefer to do this without maintaining a lot of code, you an check out this API that validates a US number and provides several formats for the number https://www.mashape.com/parsify/format

Answer 4

Look here for a code project that has a function for validating phone numbers.