Left no message

Caller ID say "CALIFORNIA"   Left no message.

I get a call at least once a day.  ID says it's a California number.  I have my answering machine on all day.  If a message isn't left I have no idea who is calling.

They have called many times, they always leave a message but it's just a high pitched beep. The Caller ID for me says "V07081642220578"

What is this?

I called the number displayed. They claim to be the National Diabetes Foundation. I checked other forums and this seems to be a scam site (wants you to provide your SSN). Does anyone actually fall for these types of solicitations?

Curious note: On the bottom of this page, "whocallsme" says the country of origin for this call is Belgium but the prefix is California. Is this a cellphone from the USA being used offshore to avoid prosecution? Maybe it's just a mistake by "whocallsme", but I wonder...