Long Term Evolution (LTE) is the recent standard of wireless communication developed by the Third Generation Partnership Project (3GPP). As the future mobile network, it is currently being rolled out to numerous areas world-wide. Besides other objectives such as enhancing the spectral efficiency and reducing latency for broadband services, LTE has been designed as a pure packet switched system. Hence, it targets the data volume requirements of cellular mobile users by increasing the peak-user data throughput to up to 100 Mbit/s . However, legacy circuit switched services are no longer supported by this technology. Contrary to the existing, wide-spread GSM network, this implies that the support of voice calls and Short Message Service (SMS) have to be realized by voice and SMS via the IP Multimedia Subsystem (IMS). In other words, voice calls are no longer separated from pure data traffic and hence influence each other.