No one was on the other side. Called back and the line was busy.

I did not answer, as I am prone to do anymore with unknown callers.  I checked this list (just Google the number), and if there is reference to the number as it was here, I just block the caller.  Minimum annoyance, maximum peace.

I answered the phone and immediately heard a "beep" but no one answered or was at the other end. It would appear to me that the purpose is to make you call back in order for them to justify any sort of telemarketing saying that you generated the call. Smells like scam to me.

Same here. No one on other end

Happen this morning and  when I  call back the line is busy.