Planetlab is widely recognized as being one of the most important Internet-scale testbeds. However, while allowing experimentations involving hundreds of hosts spread all over the world, PlanetLab still suffers of a few significant limitations. One of these limitations is the lack of heterogeneity, in particular in terms of access technologies. In this paper we describe the efforts we made, in the context of the OneLab European project, in order to mitigate this problem. In particular, we describe how we managed to integrate UMTS connectivity into a PlanetLab-based testbed. We illustrate the technical challenges we had to face, the final result we obtained, and present a case study meant to show the utility of having UMTS connectivity available in Planetlab.