Here is my 100% Achievement guide for Without Escape!
There comes a point in the game, you pick up a key from above your TV and go back up to your room.
Once that is done, you hear the phone ring just once, go back downstairs, into the living room and next to the phone (On the left hand side we got our first achievement) you see a builders leveller (a bright yellow straight looking thing)
Just pick that up to unlock this!
Hope this helps!