It sounds like a T-mobile - iPhone 4 problem. Tmobile does not support iPhone4 in all areas. We have 2 iPhone 5 and one iPhone 4S on tmobile network and the 4S does not have proper data connection. Though t-mobile support iPhones, but officially they do support iPhone 5 only. In very few markets they do have iPhone4 and 4S compatibility. It depends on where you live. I live in San Jose, CA and they do not support 4 and 4S officially here, but 5 is fully supported. Is your wife able call all other numbers without any issue from her iPhone 4?