Open charm mesons are considered as one of the most promising probes to study the propertiesof the Quark-Gluon-Plasma (QGP) which is created in relativistic heavy-ion collisions. For thedescription of the interaction of charm quarks with the QGP, for the hadronization and for theinteraction of heavy mesons in the hadronic matter dynamical models are needed. The theoreticalbasis for the description of the medium evolution and charm interactions in such models are ratherdifferent - from the solution of the Langevin equation over hydrodynamic models to microscopictransport approaches. Moreover, the models differ even in the assumption of the underlyingdegrees-of-freedom of the QGP - from pQCD massless partons to dressed heavy quasiparticles.In spite of that differences the models show a good description of the experimental observablessuch asRAAandv2. This motivated different groups, working on these charm transport approaches,to combine efforts in order to establish what one has learned so far from the comparison of themodel predictions with the experimental data as well as to establish theoretical constraints onthe models description of the charm dynamics. This contribution summarizes shortly this modelcomparison. For more details I refer to the original articles [14].