Abstract Background Shortness of breath is a common complaint among individuals contacting emergency communication center (EMCCs). In some prehospital system, emergency medical services include an advanced life support (ALS)-capable team. Whether such team should be dispatched during the phone call or delayed until the BLS-capable paramedic team reports from the scene is unclear. We aimed to evaluate the impact of delayed MMT dispatch until receiving the paramedic review compared to immediate dispatch at the time of the call on patient outcomes. Methods A cross-sectional study conducted in Lyon, France, using data obtained from the departmental EMCC during the period from January to December 2019. We included consecutive calls related to adult patients experiencing acute respiratory distress. Patients from the two groups (immediate mobile medical team (MMT) dispatch or delayed MMT dispatch) were matched on a propensity score, and a conditional weighted logistic regression assessed the adjusted odds ratios (ORs) for each outcome (mortality on days 0, 7 and 30). Results A total of 870 calls (median age 72 [57–84], male 466 53.6%) were sought for analysis [614 (70.6%) “immediate MMT dispatch” and 256 (29.4%) “delayed MMT” groups]. The median time before MMT dispatch was 25.1 min longer in the delayed MMT group (30.7 [26.4–36.1] vs. 5.6 [3.9–8.8] min, p < 0.001). Patients subjected to a delayed MMT intervention were older (median age 78 [66–87] vs. 69 [53–83], p < 0.001) and more frequently highly dependent (16.3% vs. 8.6%, p < 0.001). A higher proportion of patients in the delayed MMT group required bag valve mask ventilation (47.3% vs. 39.1%, p = 0.03), noninvasive ventilation (24.6% vs. 20.0%, p = 0.13), endotracheal intubation (7.0% vs. 4.1%, p = 0.07) and catecholamine infusion (3.9% vs. 1.3%, p = 0.01). After propensity score matching, mortality at day 0 was higher in the delayed MMT group (9.8% vs. 4.2%, p = 0.002). Immediate MMT dispatch at the call was associated with a lower risk of mortality on day 0 (0.60 [0.38;0.82], p < 0.001) day 7 (0.50 [0.27;0.72], p < 0.001) and day 30 (0.56 [0.35;0.78], p < 0.001) Conclusions This study suggests that the deployment of an MMT at call in patients in acute respiratory distress may result in decreased short to medium-term mortality compared to a delayed MMT following initial first aid assessment.