Most cell phone providers lock their phones so that they cannot be used on other networks. It’s sort of a way to protect their financial interests. But what does “unlocked iPhone 4s” mean? Well, when an iPhone, or any type of cell phone is locked it can only be used on the one provider’s service. But when it displays the message “iPhone 4s unlocked” it means that it can now be used on many other types of provider’s networks.
The trouble is that even when it is unlocked, it does not mean that it will have all the other provider’s applications available to use. Some people do not consider this to be fully unlocked. Many users feel that an iPhone is unlocked completely if all restrictions are removed and all the features are fully available. Many people refer to getting these restrictions removed as “jailbreaking.”
Many times users will not purchase a phone that is locked because they want the flexibility to be able to choose the network that they want to use the iPhone on. It is technically legal to unlock an iPhone. But Apple specifically addressed the issue by stating that an iPhone that is unlocked is void of any warranty.