A data payload is generated to describe an event, and includes a priority value indicating a level of urgency for response. Text-based notifications are generated to have text content based on the payload contents and formatted according to a format standard for one or more text transmission services, and then transmitted to user devices. Additionally, audio-based notifications, having audio content based on the payload contents, are selectively generated and transmitted based on the priority value of the data payload, on an elapsing of a time duration associated with the priority value of the data payload, and on acknowledgment states of the user devices. In this manner, a two-stage event notification providing both text-based notifications and escalated audio-based notifications is achieved.