Mine is on call Christmas Eve & Christmas Day, all day, actually for 72 hours straight - Sat through Mon. They try to rotate Christmas on call but they laid off two of the three people he rotates with and the remaining person had already requested vacation time when they laid off the other two. Making this the 3rd year in a ROW.
I almost wish he had a shift so we'd at least know he'd be gone from this time to this time and could plan around it. As it is we are never quite sure if/when he might have to work, if that work is something that can be done from home over the network, or something that has to be done in the office with the special software/hardware or something that will require him to drive 2-5 hours away and climb a tower to replace broken or damaged equipment.
Or maybe nothing at all happens & we get the OT as a nice Christmas bonus, though that has yet to ever happen.