Strange Phone Calls, AT&T not helpful...

For the past two days I have been recieving a phone call from this number: 123456789 . Seriously. I am dumbfounded first because there are not enough digits to really be a phone number, and secondly because when I clicked my phone to return the call I get 3 beeps and my phone displays "wrong number". I called AT&T to ask if they had any idea what it was or if they could check into it. They couldn't really help me, the person answering my call looked up my call history and couldn't even find that I had recieved any calls from the strange number. They did, however, note that I had made a call to 911 and was charges 50 cents by the state because of it. I did not make any calls to 911, so they refunded the 50 cents (I didn't even ask them to). SO Basically, I'm not answering my phone if the number comes up again, and if you recieve any calls from that number, don't answer.