<p>Energy demand and sustainability of telecommunication networks are of interest to both the public and the information and communication technology sector. Therefore, energy demands of three operators providing telecommunication services nationwide in Germany are reported for the study period 2009–2022—solely based on publicly accessible data. For this purpose, the relevant data were collected, and they are presented and analyzed in order to discuss related insights. Results on the annual energy demands of the operators acting nationwide in Germany show that they are in a range of several hundreds of gigawatt hours to a few terawatt hours—depending on the network’s size and its development history. For comparing different-sized networks, the annual energy demand per subscription is used. Related results are in a range of several tens of kilowatt hours. Insights are that telecommunication networks use significant amounts of energy in a developed economy and that the specific energy demand depends on the operator’s status—i.e., whether it is an incumbent operator or not. Further results show that the aggregate electricity demands of the considered telecom network operators are roughly in the order of 1% of the German net electricity.</p>