Well, I'll have a shot.
from my experience.
Did you get a CD with the new modem... this will / should contain the " driver " for the modem... driver, being a piece of software that lets the computer talk to the modem.
If no CD then get on the net and search for the driver.... probably find it in Telstra or google " driver for surfboard modem ".... then try to find the series or model of modem.
try here.................. http://www.motorola.com/Support/US-E...arging-Drivers
Also, there is a pinhole in the modem , well about the size of a toothpick circumference....... that is the re-set button. Poke a toothpick, or paperclip in that to re-set it.
Once the modem is connected you should see green lights.... static.... orange light...... flicking.... that is good.
If not working still.................... I can't help you........... sorry.
cheers Phill