To find the right strategy to save energy, knowledge of the amount of energy spent in every single action performed by the mobile phone is needed. We have made an energy measurement campaign on a commercial mobile phone, the Nokia N95. In this paper we present several results to show the impact of 2G and 3G networks on the energy consumption of the mobile device focusing on voice services, Short Message Service (SMS) and data connection. In Section II a motivation for this work is given. In Section III the test bed used for the measurements is described and the results of measurements for voice, SMS and data connection are presented and discussed in Section IV.