ok i see alot of posts about this so i would like to help clear something up.
if you are behing a router it seem all anyone ever says to connect to your telo is you need to hook a pc to the back of the unit. this is not true althought it will will work fo rthis http://setup.ooma.com .
instead of this all you really need to do if your telo is behind a router is get it's new ip address from your router and type it in. it's that easy. this is my ip address for my ooma http://192.168.0.190/ it is behind my router and and this is the ip my router has assigned it.
so if you have your ooma behind a router and need to access it, it's easier just to get the correct ip from your router then to keep playing with wires.
just trying to help.