This thesis presents the devolvement of a network emulator. The emulator, Net Devil is aimed for the telecom sector in order to resemble live networks in test labs by intercepting packets and applying rules to them. Rules such as drop, delay and discard packets can be set by the user. In order for the emulator to control all types of network traffic it is developed as a generic tool allowing the user to intercept packets with fine granularity. Furthermore the thesis presents the evolution of cellular networks, different network characteristics are discussed in order to understand why IP-traffic over these networks is more prune to errors than the wired counterpart. The thesis shows that it is possible to use an emulator tool in order to impair the network traffic in a controlled way without extensive overhead. Furthermore the use of a tool like the Net Devil might have other areas of use when it comes to network monitoring and development.