cms-service/app/Providers/AppServiceProvider.php

<?php

namespace App\Providers;

use Illuminate\Support\Facades\Validator;
use Illuminate\Support\ServiceProvider;

class AppServiceProvider extends ServiceProvider
{
    /**
     * Register any application services.
     *
     * @return void
     */
    public function register()
    {
        Validator::extend('mobile', function ($attribute, $value, $parameters) {
            return preg_match('/^1[3456789]{1}\d{9}$/', $value);
        });
    }
}