The technology which uses the telephone line and high speed does data communication. Using the high band where you do not use to conveying the sound of the telephone in one kindof xDSL technology which does communication, usingthe telephone lineof 1 pair it is used in the general joining telephone, it communicates.

The central telephone exchange which is suitable to download "asymmetry (asymmetric)" asin name, considered as user side -> user direction (the descent) as for transmission speed 1.5 - approximately 50Mbps, the user who undertakesthe uploadof the opposite -> central telephone exchange direction (rising) as for transmission speed full speed is different depending upon 0.5 - approximately 12Mbps and communication direction.

As for the band which ADSL uses because deterioration of the electric information is extreme, as for being able to utilize ADSL length of the telephone line approximately is limited to the telephone line to 6 - 7km. In addition, actual transmission speed has an influence on the distance and quality of the circuit largely even with the telephone line which can utilize ADSL. ... The continuation is read

As for ADSLbeingsomething which first is utilized in xDSL technology, to be already wide time was not required for general home in order to use the telephone line which has spread spread quickly furthermore high speed as the technology which can offerInternetconnected environment at the fee which can be utilized even with general home.

As for ADSL spread started first in America, but in US NTT east indianwest US which managesthe telephone linedisapproval had been shown in ADSL the radio interference of ISDN as a reason. And,the NTT regional company MDF which becomes necessary in ADSLconnection(the main switchboard) with easily did not permit interconnect at the ADSL enterprise, this utilization was late with cause.

But, targetting thetelephone line wherethe NTT regionalcompanyrecognizes the interconnect with MDF in 1999 December, Tokyo ? it is ? ? ?communication(at that time) and NTT -ME (at that time) and the like is accommodated in central telephone exchange of several places of the national capital region, limited commercial business service was started. Receiving this flow, the real commercial business service which designates the central telephone exchange of entire country as the object it was started in 2000 by common carrier each company, also the NTT regional company whichispassive in ADSL, commercial business service started in2000 December.

In the country at the beginningG.992.2(G.lite) the 1.5Mbps service with standard was main current, butYahoo!BBG.992.1(G.dmt) the 8Mbps service with standard start to 2001 August. In the form which follows to this other companies and successively to start 8Mbps service, it was decided that spread of 8Mbps service advance with fierce spirit. In addition, after the 2002 September,expandingG.992.1 standard individually, also the ADSL enterprise which does the service of 12Mbps appears, as the communication field whose competition is little is unusual, better-service competition between the enterprise has incandesced.