Just curious if you can and if anyone has done this? Let's say your flight has been delayed or you're arriving really late that night. Can you call the hotel and check-in over the phone?
Not sure if they would do that... after all they always want to check your id, etc. I do know many folks will call if they are going to be late - maybe after 9pm, and for sure if after midnight so they do not decide you are a no-show.
I can't speak to the Cosmo specifically, but calling ahead to reconfirm you are coming is not a bad idea. They won't check you in but it makes them more likely to hold the room.
I've done it several times to cover my ass. Once my flight got delayed and didn't land till 11PM, and another time didn't land until 3:30AM
I would call ahed and let them know you are a late arrival. I usually call a few weeks before my trip and have them note my account. As for checking in though you will need to actually go to the desk when you arrive.