ANSI T1.413 defines the requirements for the single asymmetric digital subscriber line (ADSL) for the interface between the telecommunications network and the customer installation in terms of their interaction and electrical characteristics. ADSL allows the provision of voiceband services (including POTS and data services up to 56 kbit/s) and a variety of digital channels. In the direction from the network to the customer premises , the digital bearer channels may consist of full duplex low-speed bearer channels and simpler high-speed bearer channels; in the other direction, only low-speed bearer channels are provided.
