Quality of Service markings can benefit real time traffic. A survey weconducted on a mobile cellular testbed (Monroe) has revealed howdifferentiated services traffic is treated in practical networks, and showsmany networks do not respect diffserv markings resulting unpredictable real-time performance. This motivates a change to the network programming API for real-time trafficto provide dynamic transport selection and fallback, enabling successful useof network QoS. The API is presented in the context of theNEAT[1](https://neat-project.org) open source project.