Demand for ambulances has increased significantly in recent years due, for example, to ongoing public health issues and lack of availability of alternative healthcare services. However, as demand increases, so too do ambulance waiting times, partly due to significant pressures on emergency departments (EDs) resulting in handover delays. People experiencing mental health distress who cannot access the care they need often contact ambulance services or present to the ED. Ambulance trusts across the UK are attempting to address this by employing mental health professionals (MHPs) in various capacities. In this article, the authors explore some of the issues related to mental health-related calls to 999 services. The authors then describe a service improvement initiative in Wales which involves MHPs working in 999 call centre clinical support desk services to improve the quality of care delivered to people with mental health issues and reduce demand on ambulance and ED services.