Who called from 6502129999

When I don't see caller ID, I don't answer.  Same in this case.  They've called twice and have left no voicemail.

called my cell three times in a row.  did not anser.

Keeps calling. I haven't answered but haven't gotten a voicemail like everyone else. I'm in the Bay area in California and the number appears to be out of San Mateo which is less than an hour from me. I'm wondering how they got my number? And if there is a connection between everyone else here; like we belong to the same doctors office, insurance,  company, etc..

Keeps calling every other days, but no message and hangs up very fast when picked up...I put on blocked call list in phone

Got a call from this number. the ID said San mateo. CA at 327 pm. dId not  leave a message and went to a recording. calling back got a disconnected number.....