Phone drowned; now what?

I’m a couple of months from completing an AT&T-morphed-to-Cingular cellphone account I have planned to terminate. Yesterday, my old Nokia fell (dived?) into some water and, of course, drowned. In my work, I have to have a cellphone; I want to replace my phone ASAP; I’d be fine with finishing my current contract, but don’t want to lock in with Cingular again; and I need a phone now, with my old number. How should I proceed? Thanks!