Blinking light on the DSL modem.

Most recently I found that when I turn my Speedstream 4100 DSL modem, the power light and the ethernet light come on steady but the DSL light blinks constantly between green and red. I checked the connnections both on the device as well as on the filter and all appeared well. I called the tech support and after running a check on their lines, they advised me that my modem was bad. It was running fine for the longest time and then all of a sudden it stopped. I decided to power down and then power up again. It worked fine for 2 minutes then the DSL light started blinking again and I lost connection to the internet. I tried that a few more times but to no success. Do I really need a new modem or can it be something else?