For those who want to know how to unlock iPhone 4s Verizon has attempted to make it a little more difficult. It seems they are determined to try to force customers to stay with their network or not be able to use their iPhone with other service providers. The trouble with unlocking Verizon iPhones is that the company uses a nonstandard size for their SIM cards. This is an attempt to keep customers from being able to switch them out between carriers. So even if you go through the basic steps of jailbreaking and unlocking the iPhone you would not be able to use another provider because you cannot switch SIM cards.
You can go to Verizon and pay them an extra fee to have them unlock the phone for you. There is also a way to purchase a unlocked iPhone from Apple. If it really bothers you to have to pay Verizon to unlock the phone for you there should be software released soon that will enable customers to be able to unlock the phone themselves. This is much more convenient as customers like the iPhone but need the flexibility of being able to choose which of the service providers they prefer.