I typically send an email in the morning of the day I'm working remotely with my availability schedule. If my schedule is going to be fluid, I tell folks to lo

I typically send an email in the morning of the day I'm working remotely with my availability schedule. If my schedule is going to be fluid, I tell folks to look at my Skype status--if I'm online, that means I am available. It's also advantageous to be able to simply forward your desk phone--when I'm available, my desk phone is forwarded to my mobile. When I'm finished working, the forward is deactivated (it also helps that only my direct manager has my mobile number, and he would likely only call if something had seriously blown up).