It’s called “One Ring” (or Wangiri, if you’re going with the Japanese name). The scam makes something is urgent, and they have to call back. Once they do, the person on the other line will try to stall. That’s because it’s a paid telephone service, and you’ll be charged by the minute for talking to someone on that line.
People aren’t falling for scam phonecalls anymore. In fact, unless someone knows the number calling, they rarely pick up. As a result, scammers are getting more creative.
If you see a call like this, it’s best to ignore it. Block the number and go about your day. If someone had something actually important to say, they would have left you a voicemail or sent you a text message like a normal person.
Source: Jennings Brown, Gizmodo