Perhaps I was unclear. CDMA/TDMA is the prevalent system in the U.S. GSM, the European standard, is now making a larger appearance in the U.S. If you want a single cell phone that will work both in the U.S. and in Europe, you probably want a tri-band GSM model and a service provider who provides GSM service in the U.S. and has roaming agreements in Europe. Mine does. As for dead zones, that happens no matter which system is used.
By the way since we are on the subject of cell phones, many states in the U.S. are promoting legislation which would compel the use of hands free cell phones in automobiles. I have for years used an earset with the cell phone just so I would not have to use my hands to answer and hold the phone during a call (which is the very practice that leads to vehicle accidents), but the wires were always a hassle with the seat belts and the standard shift one gets in European auto rentals. So my new cell phone is Bluetooth equipped. That allows me to wear a Bluetooth equipped earpiece that is wireless. As long as I am within 30 feet of my cell phone the earpiece will automatically answer. I don't even have to have the phone ring; the earpiece will discreetly chime in my ear when a call is incoming. It is very slick. Of course the earpiece has a flashing blue LED on it and those unfamiliar with the device think it is a hearing aid. Disclaimer: Jan thinks it looks dorky. I was in a store a month or so ago and one salesperson was raising her voice thinking it would help to hear her while her sales associate, bespeckled in piercing jewelry and knowing what the earpiece was, just kept saying, "Cool."
The best lesson one can learn in using your cell phone abroad is when to turn it off.
Tom in Carlisle