Just say Hi, and Im your new roomate.....discuss the room, key things you're bringing...then make up some shit about you have to go...lie and say you'll call them some other time
I got my roomate's name and her phone number months ago. I go to school in 8 days...I called her about 4 days ago. Thats what I told her, minus the room shit. I am gonna call her back tho, today probably. Fucking awkward, I think I'm gonna hate her. Oh well.