Porting from Optimum cable: has anyone done this?

I am trying to port my phone number from Optimum cable (aka Cablevision) to a new t-mobile line. T-mobile has given me a temporary number and I'm eager to use my old number. With my Optimum PIN number, the port failed. It turns out that Optimum doesn't use a PIN for porting. I've confirmed this with several Optimum people. They say the PIN should be left blank. So far that hasn't worked either. Has anyone successfully ported from Optimum?

PS. iPhone5 was unlocked and working with t-mobile SIM. Area code is local code (i.e. 914).