The available pay phone at D’Artagnan was broken, so I just hopped on the metro back to check out Fouconnier in person. They were booked solid for the next two nights, sorry, but you ought to do okay at MIJE, 4 Rue Teton, just a few metro stops away, here’s a metro map, on which I mark the stations for you.
MIJE is an independant hostel. There were about eight beds spread around my room, which was either locked or not by the key available at reception. I dropped off my stuff, since the lockout ran ’til 5PM, and ran off to the Louvre, ducking in a side entrance, where there were no lines for tickets. Yay.