"I am not sure how well this would work in the US as apparently you can be charged for inbound calls there."
Right, in the U.S. you're charged for "air time" on both outbound and inbound mobile calls. However, the trick would work with land-lines, and is especially useful when one party has a calling plan with flat-rate monthly billing and the other pays per-call. I had some family members who did this many years ago, long before there were mobile phones.
Answering machines (for land lines) are also designed to exploit the "missed call" trick: if I call my home answering machine to remotely retrieve my messages, it will answer on the first ring if I have messages, otherwise it will answer on the fourth ring. Thus, if it rings twice, I can hang up, having learned that I have no messages without having paid for a call. (Even if I'm calling from a mobile phone and paying for the call, I've spent much less time to find out that I have no messages.)
The only problem with this scheme is that it's somewhat unreliable. The "ring tone" that the caller hears is generated by their local exchange, and doesn't exactly correspond to the ring on the callee's phone, which is generated by the remote exchange. So the caller may hear a ring tone and hang up before the callee ever hears a ring. (At least that's the way it works in the U.S.) So it's probably more reliable to hang up after the caller hears two ring tones.
Me and my friends still do this. If one person has an unlimited or cheap contract then the person without sends a missed call and is called back.
I am not sure how well this would work in the US as apparently you can be charged for inbound calls there.