Why is my Optus ADSL dropping out when phone rings?

ADSL drop outs can be caused by a range of issues beginning with a problem with your telephone line to issues with wall sockets and in-line filter to the modem. This requires all devices to be disconnected and for each portion of the connection to be isolated and checked to determine where the problem lies, starting with connecting the modem directly to the first phone socket within you premises to eliminate internal wiring problems and an ethernet cable to check connectivity directly between your modem and a computer/laptop.