Generating Unique Phone Numbers for Testing Purposes
Leonel Elimpe
by Leonel Elimpe
1 min read


  • PHP
  • Testing


I’ve decided to document this primarily for future reference.

In an app am working on, I have a database table access_points for the model AccessPoint. This table has a column phone_number which has to be unique for each access point model. This has been a pain point during testing with respect to generating unique phone numbers to a certain degree of accuracy.

The approach demonstrated below has worked best so far.

PHP Example


use App\AccessPoint;
use Faker\Generator as Faker;
use Illuminate\Database\Eloquent\Factory;

/** @var Factory $factory */
$factory->define(AccessPoint::class, function (Faker $faker) {

     * We use anonymous function variable assignment here to assign a function
     * to the variable $randomNumber. What the function does is generate an n-digit number.
     * See below Stackoverflow answer.
     * @see
     * @param $length
     * @return string
     * @see
    $randomNumber = function($length)
        $result = '';

        for($i = 0; $i < $length; $i++) {
            $result .= random_int(0, 9);

        return $result;
     * Set the initial mobile number as a random Cameroonian number.
     * You can use a number from any network operator in your country here.
    $mobileNumber = '+237671231833';
     * Try generating a unique number by replacing the last 4 digits of the example phone number with 4 randomly
     * generated digits.
    $mobileNumberUnique = substr($mobileNumber, 0, -4) . $randomNumber(4);

    return [
        'phone_number' => $mobileNumberUnique,

If you use Laravel you’ll notice this is a model factory. You can of course move the logic into a function as necessary for your use case.

I also had to go through the trouble of using an anonymous function variable for I don’t have to declare a function that’ll be ‘hanging’ in my codebase. Might clean up the post later, but if you need any clarification, please leave a comment.