International Help

My wife was told by her corporate IT dept. that her 87XX series BB would work in Germany where she is right now on business. It is an AT&T BB that is used only as an email/internet unit and not as a phone (weird company rules).
Anyway, it doesn't work. I tried pinning her without success. I suspect that it is not automatically using a GSM network. I haver a BB Storm and am not familiar with how to set her BB to engage a GSM network. Can someone please assist? Her corporate IT dept. personnel are obviously a bunch of boobs. Thanks.