We Nod While Talking on the Phone. Design For It.

Sounds like a complex, error-prone solution that requires the devices and people to learn something new and doesn't solve the problem of not being able to see the person you're talking to.

"A nod-aware phone would make my daily communications that much more humane, and technology that much more human."

Even if you ignore the insurmountable downsides, it doesn't sound all that human to me.