public function deleteCall($index = null)
	{
		$calls = $this->listCalls();

		if ($index === null)
		{
			$index = \count($calls) - 1;
		}

		$call = $calls[$index];
		unset($calls[$index]);
		$calls = array_values($calls);
		$this->setOption('calls', $calls);

		return $call;
	}