The Verizon Wireless iPhone 4S is only a 3G smartphone that is global ready. It doesn't have the radio hardware to access the 4G LTE network.
If you had the the AT&T version of the iPhone 4S, you could access their HSPA+ network which is 3.5G or as some call it "4G with enhanced backhaul" (ie fake "4G").
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.