D-Link DSL-526B User Manual page 11

Section 2 – Installation
VCI
Most users will not be required to change this setting. The Virtual Channel Identifier (VCI) is used in conjunction with the VPI to identify the data path
between your ADSL service provider's network and your computer. If you are setting up the Router for multiple virtual connections, you will need to
configure the VPI and VCI as instructed by your ADSL service provider for the additional connections. This setting can be changed in the WAN
Setup window of the web management interface.
D-Link DSL-526B User Manual 10