Ubiquitous applications rely on the data available from sources of different nature and its collection requires careful planning to take into account their availability and accuracy. One of the base technologies of IoT and ubiquitous applications are RFID. Indeed, many data flows of physical objects can be tracked using this technology, and it is common to find heterogeneous traffics present in the same facility, each managed by different sets of readers. For example, we focus on the example of a grocery store, with two kinds of readers: (i) those for carrying out a continuous inventory process, which goal is knowing the contents of the shelves as accurately as possible, and (ii) a set of checking out readers at exit gates for the billing process that has to minimize the waiting time of customers. In this work we investigate a modification of the standard LBT protocol for RFID networks which can support this kind of multi-priority environments, by offering different qualities of service to each traffic. Results demonstrate that by tuning the protocol setup it is possible to establish a trade-off between the performance of either traffic.