I had the same problem with ignoring my "@calls" list too often, so I've been experimenting with a "@people" list instead. This includes anything where I need to get in contact with someone about something: phone calls, e-mails, talk to someone in person, write a letter, whatever.
It's true that not all those actions can be done in every context, but many (though clearly not all) of the items could potentially be done another way (e.g. calling someone I had planned to e-mail, seeing in person someone who I needed to call).
It can be difficult for me to switch back-and-forth between the "lost in my own little world of whatever I'm doing" mindset into the "interacting with other people" mindset. The idea of the @people list is to consolidate the interaction tasks, so that they're all in one place when I get into "interaction mode".
So I guess it is a legitimate "context"-- the specific communication tool is secondary to the state of mind.
Just started it recently, so I don't know how it will work in the long run, but so far so good.