Do a search on call blocking devices and phones.If its a cell phone, there are free call blocking apps out there including trac & straight talk.
http://800notes.com/forum/ta-5d4e343675a5629/call-blocking-devices
Since I get calls from different Delaware numbers multiple times a day and I know that some of them are the De. State Police scam, requesting money, I am going to guess that all of these numbers are the same losers that call on every different DE. number.