The experience of the introduction and test results from interactive television technologies (including return interactive channels) for DVB, ATSC and ISDB systems in different countries are provided in [10.3]. This model is provided in Figure 10.3. Today, the physical link for the interaction channel is mainly realized by accessing broadband (wired or wireless) IP-based networks.) At the time of writing, for digital television broadcasting, ITU-R defines certain possibility for the return interactive channel on the basis of PSTN/ISDN networks (Rec.