bp_xprofile_validate_phone_value( $retval,  $field_id,  $value, null $user_id = null )

function bp_xprofile_validate_phone_value( $retval, $field_id, $value, $user_id = null ) {

	if ( 'telephone' !== xprofile_get_field( $field_id)->type ) {
		return $retval;
	}

	if ( $retval ) {
		return $retval;
	}

	if ( false === xprofile_check_is_required_field( $field_id ) && '' === $value ) {
		return $retval;
	}

	$international = false;
	$selected_format = bp_xprofile_get_meta( $field_id, 'field', 'phone_format', true );
	if ( empty( $selected_format ) ) {
		$international = true;
	}

	$str = trim( $value );
	$str = preg_replace( '/\s+(#|x|ext(ension)?)\.?:?\s*(\d+)/', ' ext \3', $str );

	$us_number = preg_match( '/^(\+\s*)?((0{0,2}1{1,3}[^\d]+)?\(?\s*([2-9][0-9]{2})\s*[^\d]?\s*([2-9][0-9]{2})\s*[^\d]?\s*([\d]{4})){1}(\s*([[:alpha:]#][^\d]*\d.*))?$/', $str, $matches );

	$field_name = xprofile_get_field( $field_id )->name;

	if ( empty( $str) ) {
		/* SET ERROR: The field must be a valid U.S. phone number (e.g. 888-888-8888) */
		return sprintf( __( '%s is required and not allowed to be empty.', 'buddyboss' ), $field_name );
	}

	if ( $us_number ) {
		return $retval;
	}

	if ( ! $international ) {
		/* SET ERROR: The field must be a valid U.S. phone number (e.g. 888-888-8888) */
		return sprintf( __( 'Enter valid %s', 'buddyboss' ), $field_name );
	}

	$valid_number = preg_match( '/^(\+\s*)?(?=([.,\s()-]*\d){8})([\d(][\d.,\s()-]*)([[:alpha:]#][^\d]*\d.*)?$/', $str, $matches ) && preg_match( '/\d{2}/', $str );

	if ( $valid_number ) {
		return $retval;
	}

	/* SET ERROR: The field must be a valid phone number (e.g. 888-888-8888) */
	return sprintf( __( 'Enter valid %s', 'buddyboss' ), $field_name );
}