As described by the TechCrunch article titled "PSA: Missed Call From A Mystery Number? Be Careful", it advises against answering/calling back numbers that you don't recognize.
The trick? They only let the call ring once before it automatically hangs up. One ring is enough for the number to show up on your missed call screen, but just short enough that you’re not likely to answer it in time (which keeps the call from fully connecting and thus keeps the scammer from having to front for any long distance fees.)
Well, today, I've gotten 4 calls from similar numbers
I hope this serves as some record to the numbers that they used.