>You mention that Sprint and Verizon have significant CDMA networks. What is their migration strategy for 4G? To my knowledge the only 4G standard in use is fro

>You mention that Sprint and Verizon have significant CDMA networks. What is their migration strategy for 4G? To my knowledge the only 4G standard in use is from GSM. I think you are confusing the terms. GSM is a family of standards some of which are based on CDMA, like aforementioned UMTS which is the most widely deployed network standard in the world right now. Because UMTS was not based on TDMA it was a very costly upgrade for most operators since it required entirely new equipment. LTE on the other hand is yet another completely different beast (OFDMA) not compatible with any existing infrastructure so everyone has exactly the same migration strategy to LTE regardless if they are CDMA or TDMA based.