David Pogue, a tech writer for the N.Y. Times recently wrote about the new iPhone 4: For iPhone, Almost Heaven, (February 2, 2011, N.Y. Times) This is Apple's iPhone using Verizon rather than AT&T. With a different wireless carrier comes a different technology. Mr. Pogue's article is a nice succinct description of the differences between the two wireless networks in the USA and elsewhere.
[T]here are two kinds of cellphone networks in this country. They’re known as C.D.M.A. (Verizon and Sprint use this technology) and G.S.M. (the system for AT&T and T-Mobile). Making an iPhone that works on a C.D.M.A. network entailed four adjustments, some of which you won’t like.
First, Apple moved the volume and Ringer Off switches a fraction of an inch to accommodate the C.D.M.A. antenna inside. It’s not a big deal, but those buttons no longer fit existing AT&T iPhone cases. (Contrary to blogger belief, the redesign doesn’t help with the famous Death Grip issue, in which holding the phone in a certain way makes your signal bars drop. Then again, the problem emerges only when you’re in a very weak signal area, so you’ll see it less often on Verizon. I couldn’t reproduce it at all.)
A second C.D.M.A. difference: When you exchange long text messages with non-Verizon phones, they get split up into 160-character chunks. G.S.M. phones are smart enough to reconstitute those chunks into one more readable, consolidated message.
Third: You can’t talk on an C.D.M.A. phone while you’re online. That is, if you’re on a call, you can’t simultaneously check a Web site or send e-mail over the cellular network — and, annoyingly, the Personal Hotspot feature cuts off. (It reconnects when you hang up.)
For business travelers, the fourth C.D.M.A. difference is the most disappointing: not many other countries use C.D.M.A. The Verizon iPhone works in about 40 countries, including Mexico, Canada and China; AT&T phones, on the other hand, work in 220 countries. (In both cases, you pay through the nose if you use them overseas.)So now I will be able to understand the wireless telephone commercials on T.V. and elsewhere a bit better.