As the 3rd Generation Partnership Project is in the process of defining the Long-Term Evolution (LTE) of 3G, there is a high need for evaluations of different approaches in this future cellular system. One of the most significant changes with LTE, compared to current and earlier cellular telephone systems, is that it is aimed to be an all-IP network where only packet switching is supported. For example, this means that the voice service will no longer be utilizing separate circuit switched channels. Even though this IP-only approach allows for streamlining the system for packet services, which will lead to great improvements in the form of higher bit-rates, lower latencies and a wider array of service offerings, it also poses new challenges that need to be overcome. This master's thesis investigates the effects that different Quality of Service associated scheduling strategies impose on the performance of mixed services over LTE. A traffic scenario where all users engage in both a Voice over IP (VoIP) conversation and a video session is applied in an extensive network simulator. The Session Initiation Protocol is used to set up the media connections. In some of the performed simulations, separate presence service users were included in the system, with the aim to analyze the effect of the presence noise that they introduce. The simulation results indicate that prioritization of the setup messages is highly recommended in order to ensure their delivery and the completion of multi- media telephony session setups even if the system load is high. Furthermore, this study finds that it is possible to prioritize the VoIP traffic relative to the video traffic and thus heavily increase the VoIP capacity without significantly harming the quality of the video service. This gives operators the opportunity to, in the case of a highly loaded system: guarantee high voice quality even if no video can be delivered due to the high load. Regarding the effect on the mixed service users, caused by the additional presence users, no significant change in the performance could be measured with the applied 200 presence users per cell, no matter if the presence messages were prioritized higher or equal to the media traffic.