Cod zombies for iPhone help !!

How do I get call of duty zombies for free on my iPhone ?
Note I have a first gen iPhone.

I’m not really sure, but there was that thing, called “jailbreaking” I’m not really sure.

It doesn’t work on the FIRST GENERATION iPhone. You still have that?! It works on newer generations.

Switch to iPhone 4S/5 dude…

Yah, that’s not going to happen. As mentioned before, you need to get a newer IPhone (preferably the most recent) to play the game. And there’s no way to get it for free.