In this work we study the performance of a heterogeneous wireless sensor network which consists of 4 different hardware platforms (TelosB, SunSPOT, Arduino, iSense). All hardware platforms use 802.15.4 compliant radios. Due to partial implementation of the standard, they do not communicate out of the box. A first contribution of our work is a careful description of the necessary steps to make such a heterogeneous network interoperate. Our software code is available online. We deploy a heterogeneous network testbed and conduct a thorough evaluation of the performance. We examine various network performance metrics (e.g., transmission rate, receiving rate, packet loss, etc.), and assess the capabilities of each device and their intercommunication. We used different setups (e.g., distance between transmitters and receivers, etc.) to better understand the network limitations for each hardware platform.