File under things-that-surprise-by-actually-working.
In my basement apartment I was unable to make cell calls with AT&T. Most of the time I'd just get "call failed" and it wouldn't go through.
The zBoost actually works. I attached the antenna on the outside of the building and ran the cable to the unit inside. I now get full bars and perfect phone calls. Can be picked up for around $230, not inexpensive but preferable to paying for a landline.