本ETS是基于PSTN和ISDN向DVB系统提供返回信道的基准规范。注意，DVB不打算指定与每个广播系统相关联的返回信道解决方案，因为传输返回信道的不同传送媒体的互操作性是可取的。因此，返回通道的PSTN/ISDN解决方案适用于卫星、有线电视、SMATV、地面、MMDS或任何未来的DVB广播系统。这里为通过PSTN/ISDN的返回通道提供的解决方案是为DVB广播系统实现交互式服务的更广泛替代方案的一部分。

This ETS is the baseline specification for the provision of return channel based on PSTN and ISDN to DVB Systems. It is noted that the DVB does not intend to specify a return channel solution associated to each broadcast system because the interoperability of different delivery media to transport the return channel is desirable. Therefore the PSTN/ISDN solutions for the return channel apply to satellite, cable, SMATV, terrestrial, MMDS or any future DVB broadcasting system. The solutions here provided for return channel through PSTN/ISDN are a part of a wider set of alternatives to implement interactive services for DVB broadcasting systems.