I think that caller id is unique for each call they make. That way they can tell which call made a complaint about or files a grievance against them. (Just a guess.) Had the same call with no voice message so I blocked the caller. This has been one of several with the same sort of caller id but different phone numbers. Also they are probably telemarketers using several numbers. I've had similar calls before offering lower credit card rates.

Received call from this number 516-200-6247 Glen Head, NY and actually answered it.  It was the annual fund raiser for Veterans Support looking for one time pledge donations to help the hospitalized veterans and homeless veterans.  I have no problem helping our Vets.

Then you should have really helped them instead of giving money to some boiler room crook.

Telemarketing call for "mortgage rate reduction." I'm not even sure that 200 is a legal exchange. Probably a spoofing caller id.