src/Form/Element/Phone.php
public function getValidator()
    {
        if (null === $this->validator) {
            $validator = new RegexValidator('/^([\+][0-9]{1,3}[ \.\-])?([\(]{1}[0-9]{1,6}[\)])?([0-9 \.\-\/]{3,20})((x|ext|extension)[ ]?[0-9]{1,4})?$/');
            $validator->setMessage(
                /*@translate */ 'Please enter a phone Number. You can use the intenational format. Only digits and \'+\'.',
                RegexValidator::NOT_MATCH
            );

            $this->validator = $validator;
        }

        return $this->validator;
    }
public function getValidator()
    {
        if (null === $this->validator) {
            $validator = new RegexValidator('/^([\+][0-9]{1,3}[ \.\-])?([\(]{1}[0-9]{1,6}[\)])?([0-9 \.\-\/]{3,20})((x|ext|extension)[ ]?[0-9]{1,4})?$/');
            $validator->setMessage(
                /*@translate */ 'Please enter a phone Number. You can use the intenational format. Only digits and \'+\'.',
                RegexValidator::NOT_MATCH
            );

            $this->validator = $validator;
        }

        return $this->validator;
    }
Get a validator if none has been set.
https://github.com/posabsolute/jQuery-Validation-Engine/issues/265
@return RegexValidator