Caller ID came up "Unavailable". No message. Blocked caller #748 (two Panasonics + 20 ATT IDs), idiot call #1600 (not including apparent mis-dials and obvious political calls) since 5/2/13. Caller ID "1" (100-000-0000) has called 70 times, including 12 in one day, 6 on another. I also had to block my own scammed number as four times the caller ID indicated that I received a call from IT!
I have received scam IRS calls from four different numbers threatening prosecution.
All of these numbers have been kept on a spreadsheet with dates and number of calls. Since both blocking systems are now full, I have been recycling the older dated numbers that only called once or twice.