Channel bundling is the combination of several individual channels into one broadband transmission channel. In the case of ISDN, by combining several B channels, one channel with a transmission speed of n*64 kbit/s can be made available to the user.
The same technique is used with analog modems. In the Data Over Cable Service Interface Specification, DOCSIS 3.0, the standard for cable modems supports channel bundling of four or more cable channels in order to increase the data rates in the upstream and downstream.
With ADSL, data rates are increased by means of channel bundling. With ADSL, for example, the copper pairs of two ADSL connections can be combined to form one with a higher data rate. Since ADSL modems are designed for only one line pair, this can be circumvented by multipath routing or by using the multilink PPP protocol for ADSL. A different technique is used with VDSL2, namely line bonding, in which multiple lines are connected together.