BACKGROUND: Health care providers are paying more and more attention to clinical handovers. Previous studies have found that poor handovers resulted in adverse effects for patients. This study aims to determine the effectiveness of the standardized pre-notification process, from emergency medical services (EMS) to in-hospital care, with specific cognitive aid based on ATMIST. METHODS: In February 2018, a prospective field test of the effectiveness of a standardized handover tool based on the ATMIST acronym was conducted in 11 Prague hospitals. The Emergency Medical Dispatch Centre used the form to record the information from the Crews (Protocol 1). The hospital dispatch centre (Protocol 2) used the same form to record the information from the EMS Dispatching. Both protocols were then compared and monitored to determine whether the information from the field was correctly transferred to the hospital. Signature items from the ATMIST form in different groups were empirically set to find out if the level of awareness of the personnel differs between groups. RESULTS: Two hundred and sixty-nine Protocols 1 and 2 (37.41% of all pre-notifications) were analysed. There were 7,262 possible pieces of information to be transferred in total. 82.78% (n=6012) of all information was transferred correctly. The group analyses show no differences between the clinical condition of the patient and the awareness of the health care providers. CONCLUSION: This is first study evaluating the use of a standardized handover tool for telecommunication handover. The clinical condition of patients did not play any role in how the information was transferred.