The rising number of implantable devices has led to an increase in device-related workload, e.g., regular interrogation follow-up visits. Telemonitoring systems for implantable cardioverter-defibrillators (ICDs) seem to be a promising tool for reducing workload and costs, and they have the potential of optimizing patient care. However, issues such as practical functionality of ICD telemonitoring in daily routine may affect its broad implementation. The objective of this study was to evaluate potential problems during the implementation of a telemonitoring system, Medtronic CareLink™ (CL™) with respect to the installation and data transmission process. A total of 159 patients with ICDs who were equipped with the CL™ system were evaluated and followed up for 16 months regarding the success rate of the first data transmission via the telemonitoring system. In this cohort, a high rate of nontransmission of 23.9 % was observed after the 16-month follow-up. A detailed interview of these patients (no transmission) revealed that the main reasons for failed transmissions were due to the patients' loss of interest in the concept (approximately 50 %) as well as technical problems (approximately 25 %) with setting up the system. These results indicate that telemonitoring systems bear potential problems and that the evaluation of patient motivation and technical support options seems to play an important role in establishing the functionality of these systems.