Been receiving calls and hang ups from this number for the past few days.  Redial says number not in service.

don't know who this is

I to have been getting calls from this #.when i call back it says its a disconnected number.

I have had 4 calls from this number in 2 hours. If I answer, the call disconnects. .

I received one phone call from this number on my cell phone yesterday.  Didn't answer because I didn't recognize the number.   When I hit send to redial I got a recording saying that this number was no longer in service!   I've gotten calls from other numbers like this in the past . . .  how do they go through with this disconnected number to our phone?