This is a problem that just started happening fairly recently. When I call someone or receive a call, sometimes it will sound trashed, for the lack of a better word. It's just very static/unclear and you can barely make out what the other person is saying. If I hang up and call them back, usually it goes away.

Another problem is sometimes people say they can hear me but I can't hear them. When this happens, I can hear myself through the phone.

Anyways, just trying to figure out if this is a problem with my iPhone or T-Mobile.

It seems like the problem is more frequent now. I would say 90% of incoming calls now just result in me talking to myself and the person on the other line thinking I'm crazy because they can hear me but I can't hear them.

That is funny you say that... My brother is having a VERY similar problem and we can't find out what is causing it. He has the opposite problem where I would here the static and he can hear me, but in essence is still talking to himself.

Also just as you said it is happening more frequent now (his phone is AT&T tho and not unlocked/JB'ed)...