use Symfony\Component\Form\FormBuilderInterface;
 use Symfony\Component\Validator\Constraints\NotBlank;
 
 use Symfony\Component\Form\FormBuilderInterface;
 use Symfony\Component\Validator\Constraints\NotBlank;
 
         */
        public function buildForm(FormBuilderInterface $builder, array $options) {
                return parent::buildForm($builder, $options)
         */
        public function buildForm(FormBuilderInterface $builder, array $options) {
                return parent::buildForm($builder, $options)
-                       ->add('phone', TelType::class, array('attr' => array('placeholder' => 'Your phone'), 'constraints' => array(new NotBlank(array('message' => 'Please provide your phone')))));
+                       ->add('phone', TelType::class, ['attr' => ['placeholder' => 'Your phone'], 'required' => false]);