Up until the early 1990s, it was not thought possible that a television programme could be squeezed into the limited telecommunication bandwidth of a copper telephone cable to provide a video-on-demand (VOD) television service of acceptable quality, as the required bandwidth of a digital television signal was around 200 Mbit/s, which was 2,000 times greater than the bandwidth of a speech signal over a copper telephone wire. VOD services were only made possible as a result of two major technological developments: motion-compensated DCT video compression and asymmetric digital subscriber line (ADSL) data transmission.[10] Motion-compensated DCT algorithms for video coding standards include the H.26x formats from 1988 onwards and the MPEG formats from 1991 onwards.[11][12] Motion-compensated DCT video compression significantly reduced the amount of bandwidth required for a television signal, while at the same time ADSL increased the bandwidth of data that could be sent over a copper telephone wire. ADSL increased the bandwidth of a telephone line from around 0.1 Mbit/s to 2 Mbit/s, while DCT compression reduced the required bandwidth of a digital television signal from around 200 Mbit/s down to about 2 Mbit/s. The combination of DCT and ADSL technologies made it possible to practically implement VOD services at around 2 Mbit/s bandwidth in the 1990s.[10]