Who was Oliver talking to in that trailer?

There's plenty of threads where the 3 minute trailer has been posted, so I won't be bothering to post it again here. But at one point in that trailer, Oliver says, "Slade Wilson is alive" and a woman says, "How is that possible? You killed him," with Oliver answering, "I don't know, but this time I'll make sure he stays dead."



Who is this woman he's talking to? It isn't Laurel or Sara; in all honesty, it almost sounds like Shado.....