For SMS, the results show that sending text messages using 3G is more energy consuming than using GSM. Moreover, we showed that the received signal strength has a high influence on the time needed for sending the message and therefore the energy. Regarding voice services, we showed that being connected to the 3G network causes the phone to consume around 50% more energy. In fact, making a one hour call with GSM instead of UMTS, allows the phone save the amount of energy needed to send more than 1000 SMS of 100 bytes. On the other hand, when a data connection is needed, 3G networks offer higher data rates with lower consumption in terms of energy per bit. Most users have the possibility to set the network they would like to use, which gives them the possibility to switch between networks depending on the actual used service. To simplify this method for energy conservation, it is possible to develop a middle-ware solution that handles the switching depending on the used applications in a automated fashion. From a network operator point of view the question whether to use 2G and 3G is not based on the energy consumption but on the capacity of the available networks. Nevertheless as pointed out before also network operators have an interest to increase the battery life of the users’ phones.