The "world phone" statement by Apple is a marketing ploy.
If you with Verizon you can have a verizon micro sim that allows you to roam on GSM networks while overseas is my understanding of how they can legally claim to be a "world phone."
Verizon and Sprint have set ESNs for their networks. They probably will not approve the ESNs of unlocked iPhone 4S devices.
I just read that. I don't understand that statement at all.
The Verizon iPhone 4g or 4gs that is jail broke can work with other carriers which as cricket, tmobil.
The unlocked iPhone works only on supported GSM networks, such as AT&T in the U.S. When you travel internationally, you can also use a micro-SIM card from a local GSM carrier. The unlocked iPhone 4 will not work with CDMA carriers such as Verizon Wireless or Sprint.