Wikipedia
DVB-RCT (Digital Video Broadcasting - Return Channel Terrestrial), provides a method by which the DVB-T (and in theory DVB-T2 but DVB-T2 probably trialled first about 5 years after last DVB-RCT field trial) platform can become a bi-directional, asymmetric, data path using wireless between broadcasters and customers. DVB-T when completed with DVB-RCT can be used not only for Interactive TV (voting, quiz, etc.), but also for light IP telecommunication services. Various degrees of interactivity could be offered, without implying any return channel back from the user to the service provider: data carrousel or Electronic Programs Guides ( EPG) are examples of such enhanced TV services which make use of “Local Interactivity”, without any return path from customer to provider. To implement new interactive services having a closely coupled and real-time relationship with the TV programs (e.g., interactive advertising, tele-voting, tele-quiz), a low latency return channel technology is mandatory, and this is the goal of the DVB-RCT. Without adding a cellular style network with about x20 more masts no Internet usage except about 1/20th speed of analogue dialup would be feasible.