hey guys..can help me out with this prob..

the place im staying at has 2 phone lines..one is mine and one is another housemate's. The prob is, when they turn on their modem provided by tmnut, my dsl light will flicker and resync but now when they turn it on my dsl light just disappears and i cant connect or do anything. Restarting the modem+router(aztech dsl605ew) doesnt help at all.

as far as i know this should not happen right?