Frontier does. Some gate agents are nice and will do it for you at the gate. A few will make you call the phone number and wait 20 minutes on hold to list, even though they are doing nothing. I missed a commute home once because I got in late from a trip, ran over to Frontier hoping to get on, and the agent made me call the number and I was stuck on hold for 25 minutes. In the mean time, two other pilots showed up and took the jumpseats.