public function is_phone($type=null) {
		if (! \is_null($type)) {
			// We want an array with lowercase strings.
			r_cast::array($type);
			foreach ($type as $k=>$v) {
				if (\is_string($type[$k])) {
					$type[$k] = \strtolower($type[$k]);
				}

				if (! $type[$k]) {
					unset($type[$k]);
				}
			}

			if (! \count($type)) {
				$type = null;
			}
		}

		return (
			(false !== $this->phone) &&
			(\is_null($type) || \count(\array_intersect($type, $this->phone['types'])))
		);
	}