The function of the Integrated Security Service (ECU 911) is to receive emergency calls and coordinate the response through various emergency services. These interactions are recorded and stored as a backup of each call. The present research proposes the pre-processing of the text contained in said calls through the application of selected text formalization techniques, such as the use of dictionaries of idioms, consultation in the Dictionary of the Royal Spanish Academy (RAE), the use of spell checkers and Named Entity Recognition (NER). A bitmap is proposed as an auxiliary tool to facilitate decision-making and correct formalization during the formalization process. Finally, the score obtained by a semantic comparison model is evaluated, in which the informal transcribed text of the calls is compared with the formalized text to determine whether the formalization of text improves the performance of the Artificial Intelligence models The results demonstrated that performance was improved or maintained in 74% of the test cases thanks to the combination of these techniques. .