The project X-TEAM D2D (Extended ATM for Door-to-Door Travel) has been funded by SESAR JU in 2020 and completed its activities in 2022, pursuing and accomplishing the definition, development and initial assessment of a Concept of Operations (ConOps) for the seamless integration of ATM and air transport into an overall intermodal network, including other available transportation means (surface, water), to support the door-to-door connectivity, in up to 4 hours, between any location in Europe. The project addressed the ATM and air transport, including Urban Air Mobility (UAM), integration in the overall transport network serving urban and extended urban (up to regional level) mobility, specifically identifying and considering the transportation and passengers service scenarios expected for the near, medium and long-term future, i.e. for the project baseline (2025), intermediate (2035) and final (2050) time horizons. In this paper, the main outcomes from the project activities are summarized, with particular emphasis on the studies about the definition of future scenarios and use cases for the integration of the vertical transport with the surface transport towards integrated intermodal transport system and about identification of the barriers towards this goal. In addition, an outline is provided on the specific ConOps for the integration of ATM in intermodal transport infrastructure (i.e. the part of the overall ConOps devoted to integration of different transportation means) and on the specific ConOps for the integration of ATM in intermodal service to passengers (i.e. the specific component of the ConOps devoted to design of a unique service to passengers). Finally, the main outcomes are summarized from the validation of the proposed ConOps through dedicated simulations.