The SimulaMet OpenAirInterface VNF is a complex 4-VDU VNF, allowing its users to instantiate and maintain a tailor-made Enhanced Packet Core (EPC) for 4G/5G mobile broadband testbeds. The EPC components are directly built from their sources during instantiation, allowing to use customised versions according to the users' needs. A general overview has already been presented during the OSM Hackfest in March 2020. In this presentation and live demonstration, we would like to highlight the solutions chosen to efficiently use OSM for handling the instantiation process, provide telemetry, and to debug issues. That is, we particularly would like to present to the audience the lessons learned during the ongoing development. Finally, we would also like to show the audience a live demo of an OSM-managed 4G testbed setup with telemetry collection.