In the demarc on the side of your home, (if a Tech came to your home to install/activate service) the Tech may of put in a POTS splitter. It sends the DSL signal to a dedicated outlet. It removes the need to have DSL filters on each phone.
With you being on a dryloop, the POTS splitter could be removed, or the Tech can wire in your upstairs outlet for the Telus Gateway to plug into instead.
The other alternative is to put a splice block in your demarc, allowing for two outlets to be able to be used for the Telus gateway(only 1 gateway used at a time). Thats if you are inclined to move your Gateway around the house.
Another possibility is if there was 2 pairs coming into the home(2 service). One was deactivated.
I'm more curious about the ethernet jack. Is it an actual ethernet jack you can plug a network cable into? If yes, do you know where the other end of the line running to that ethernet jack is? If it's near where the modem was installed originally, that could be a bonus for you.