I've been getting these calls quite a few times the past few days. They leave no message and call back often. Since we don't know anyone with that area code, we don't answer it. My thinking is that if you don't have call ID turned on, they have your number to make unauthorized calls charged to your number. If that's the case, report all calls made to your telephone number and call your telephone carrier. We have ATT Cellular and they're very efficient about removing those charges made that show up on your bill.