iPhone without a SIM card as an iPod touch? Can I use an iPhone without a SIM card as an iPod touch?

I do not know the previous carrier, because the Iphone was reset and has no sim card.

Is there any way I can use it as an iPod touch (without activating it) ?
First of all Im assuming that you are in the welcome menu and you cant pass this screen: 



So I know there is a way to activate it with RedSn0w but I dont know if it works with iOS 7 so I would recommend you to check that option.

Or you can UNLOCK it via IMEI and then activate it with any SIM.