Upgrade VDSL modem firmware on a Cisco 880 Series Router

Firstly transfer the new firmware to your router’s flash memory using tftp. Next enter config mode and type:

router(config)# controller vdsl 0

Then type the following command at the prompt, where YOUR_FIRMWARE is the name of the firmware file that you transferred to flash e.g. vdsl.bin-A2pv6C035d_d23j which is the recommended firmware for BT ADSL in the UK.

router(config-controller)# firmware filename flash:YOUR_FIRMWARE

Refs:

Cisco BT xDSL Product Bulletin

A2pv6C035d_d23j Firmware Release Notes