G.992.1 whichis oneof the ADSL standard which ITU standardizes(G.dmt) at one of incidental standard, standard for the high speed ADSLin US. Each company following one another in 2003, 20Mbps which starts it is adopted forsuperADSL connection service.

WithG.992.1 it descended and the frequency zone 138 - 1104kHz was usedasa one for communication, but with Annex I the upper limit is pulled up to 2 times, can utilize to 2208kHz technology is adopted. Because of this, there is a weak point, the signal is attenuated substantially at the railroad track length which is shorter than past, each company above fixed distance offers the function whichis changed tothe communication automatically with Annex C