problems making/receiving calls while in the US?

I am having problems making/receiving calls while in the US.
When connecting to the At&T network: I can make outgoing calls but any incoming calls goes to voice mail.
When connecting to the T-mobile network, I can receive calls, but when I tried to make outgoing calls, it disconnects after talking for 2 minutes.
Other networks didn't work. I am now in Wisconsin.
Data works fine. SMS works fine.
Thanks