Originally cellular networks handled calls and short messages only. Today, this has been extended to handle packet data services. However now the world is moving towards an entirely IP based mobile service based on LTE and the Evolved Packet Core. Security becomes even more important than before. Cellular networks will be using the same technology that runs the Internet, which could leave them open to a range of threats from the air interface side of the network, especially with the popularity of smart phones and USB "Mobile Broadband" modems. This thesis investigated a range of network protocols used in the Evolved Packet Core, as well as the possibility of attacks against these networks and their protocols and whether such attacks can be achieved, especially from cheap handheld devices. Further this thesis presents results showing that these network protocols are free from serious flaws in their specification.