When SMS first launched it seemed kind of useless to me (there was a lot that the agents couldn't do) but lately it's gotten a lot better -- it seems that they can do anything that a phone reservation agent can do? Lately I've had a friend confirm a SDC (even changing to a coterminal) and had a different friend fix a "not waitlisted" problem after a SDC, all through SMS.

I assume that the web chat (which I didn't know about until you posted it) and the SMS go to the same agents. Web chat is especially welcome -- it can work if you are in a place where you can't call (eg, on a plane) even if your carrier doesn't support wifi calling/texting