The hacker community has found many workarounds, most of which are disallowed by Apple and make it difficult or impossible to obtain warranty service. "Jailbreaking" allows users to install apps not available on the App Store or modify basic functionality. SIM unlocking allows the iPhone to be used on a different carrier's network. However, in the United States, Apple cannot void an iPhone's warranty unless it can show that a problem or component failure is linked to the installation or placement of an after-market item such as unauthorized applications, because of the Federal Trade Commission's Magnuson-Moss Warranty Act of 1975.