It is of interest to understand the life cycle contribution from the use of smartphones including their network usage, as well as to gain knowledge regarding the impact of the smartphone as a device to provide input for network studies. This cradle-to-grave study is based on life cycle assessment (LCA) methodology as outlined by the ISO14040 series and the supplementing ICT specific LCA standard from ETSI/ITU. The paper provides details regarding data collection, assumptions, methods and results. Furthermore, sensitivity analysis results for selected parameters are presented, including variations due to different secondary data sets. This study calculates the Global Warming Potential (GWP) for the assessed smartphone (a Sony Mobile Z5) including accessories) to 57 kg CO2e for an assumed operating life time of 3 years, excluding the network usage. Results are also presented for other impact categories and as yearly figures. In addition, the distribution of impacts between life cycle stages is provided for the assessed impact categories. Integrated circuit (IC) production is identified as a major contributor to the overall impacts followed by the production of the display. For GWP specifically, overall results are also provided including the network usage