What carriers are using what signals?

With so many carriers out there and many different signals, who is using what? I will tell you, grouping them by signal type. CDMA is what the US started with as the first cell phone signal, and therefore has the most coverage area, simply because we have been building the towers for that type of signal the longest. The more major carriers on this signal are: Verizon, Sprint, AllTel, and US Cellular. The next largest in coverage area(in the US) is GSM. These carriers include: Cingular (now AT&T) and Tmobil. The third major signal is IDEN and is primarily used by Nextel (now merged with Sprint). Please keep in mind there are exceptions to every rule, such as some companies have "world phones" meaning they can be swapped to and from CDMA and GSM. With this type of phone you can easily use the signal here or overseas, by just setting the device accordingly.