If his thought phone really works, then he should be getting a handful of calls right now and his thought-message-box is likely full!
Or maybe he's got thought-waiting?
Or if he's somewhere else, thought-forwarding?
Would you get a busy signal if he's thinking about somebody else when you tried to think about him?
How do you hang up on a thought?
What does a thought-"ring" sound like?
If a thought-phone rings in the forest, and nobody is around to hear it, did it really do any thinking of thoughts?
What happens if you dial a wrong thought-number?
Does the person at the other end hear your thoughts regardless?
Who exactly is the thought-operator?
Who runs the local thought phone company?
Are there many choices when it comes to long distance thought plans?
Are thoughts cheaper at nights and on weekends and holidays?