Call of Duty: Zombies on Iphone stopped working?

So when I first DL this game it worked fine, but all of a sudden when I try to get online it says,"can't access online services, please try again later." So it's been saying this for months now. Before my last phone update it stopped working so I did the update and no change. I've deleted the app and reinstalled several times, disconnect and reconnect from Wi-Fi, tried playing in other Wi-Fi spots where I used to play thinking it might my my internet, but still doesn't work. I've talked to Activision and they were no help. They told me to do a port forward but don't see the point if it's not working in other Wi-Fi spots where it use to, plus I don't have a computer and doubt I can do that via iphone. Anyone have a clue what else I can do?

Call customer service about the phone if no help there

it could be the game servers being down