So my internet will be coming in....I'm getting at&t internet service( usa people on here should be familiar with this)...it is high speed internet and will be dsl based....meaning I will also receive free dial up as part of my package. now here is my question... i just recently bought a 3 way inline coupler, this:

with this, if my modem for dsl is plugged into the left and my dreamcast into the right...will this give me Both connections that I want successfully? and those are r j 11 jacks by the way