I Have Verizon & Live in Chicago And We Can't Make Calls To T-Mobile Users.

It's Just T-Mobile Users having this problem. It's official people, T-Mobile Sucks!
And I would love to talk to you, but the call won't go through to you...

ENGADGETMOBILE.COM -- We're getting reports from sea to shining sea this evening that T-Mobile service is down or intermittent on both voice and data -- particularly bad timing in light of the recent Sidekick drama. We've tested in New York and it's definitely down for us -- both voice and data -- so how's service treating everyone out there?

Source: http://www.engadgetmobile.com/2009/11/03/t-mobile-usa-do