Whilst in the early stages of the telecommunication age point-to-point connections were commonly established via permanent landline connections, the standard point-to-point connection is now based on a superordinate network hierarchy. SDH or ATM networks, for example, are used to establish the permanent connections virtually. Depending on the connection type and speed, customer connections are based on copper pairs, coaxial lines, or fibre optics. The data transmission rate ranges from 64 kilobits per second up to standard point-to-point connections of 155 megabits per second or higher. G.703 or X.21 are typical interfaces for the common 2 Mbit point-to-point connection.