What will happen to my iphone 5?

So I'm on an AT&T family plan and something came up and the main lines aren't gonna be able to pay their bill and our phones are gonna get disconnected. I barely had this iphone for about 2-3 weeks and it sucks that its gonna get disconnected. I was just wondering if I will able to reconnect it or will it just be locked? What's the best thing to do in this situation? Can I try Connecting it to other companies or do I have to stay with AT&T?

You can buy a sim card from t-mobile for cheap, and put it in the phone.
Also, the phone will act just like an ipod without service.

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