repeat calls. no message left

These people are potential scam artist, also they may be a front for all sort of danger due to my knowledge possible Human Traffickers there able to get in to facebook accounts and twitter accounts to Learn information

Caller ID shows "California".  Whitepages.com lists as "telecom routing administration, landline, California.
No message left when answering machine picked up.

Someone called me from this number. Picked up, no one answered on the other side.