As a Getting Things Done practitioner I used the suggested @Call context for phone and email. Then, when I began using ResultsManager, I shifted to its default of @Phone.
This morning I’ve shifted again to the more generic @Contact context. As long as I know I have to contact someone it doesn’t matter if I use the phone, email, SMS, carrier pigeon, telepathy or face-to-face conversation. It also serves in the other direction for any @Waiting For items from other people. I expect some sort of contact from them.