Caller id says Unknown. They have called my cell phone and house phone a couple of times each and not left a message. I have a google voice number also and when both phones ring at the same time I know it is my google voice number being called. I will block it now and they won't call again through that number.
Spam caller; I reported it. It AUTOMATICALLY-DOES-NOT-RING: On my cell phone, I've installed "Call Blocker Free - Blacklist" by NQ Mobile Security for Android phones. It is useful for non-business phones to only accept calls from phone numbers I want, incoming unwanted calls automatically do not ring (rings on the spam caller end of the call, but not the recipient end and shows in the app instead of the phone call log). I go to the app>Main screen>Funnel icon>Blocking mode> change it to: "Accept ONLY FROM WHITELIST and CONTACTS". Add the phone numbers you wish to receive calls from to your Contacts (keep your Contacts up-to-date as normal) and/or add non-contacts that you wish to receive a call from to the app Whitelist. With my phone carrier service, I also turn voicemail OFF so that it doesn't pickup a spam call after its set time to record.
UPDATE: I'm liking "Call Blocker" by embware for Android phones better for the same and additional capabilities. It has the added ability to add a blocked non-spam number chosen from the blocked call log to the unblock-whitelist, with a name so I know the name associated with the phone number. And, it has the added ability to allow one-click-calling a whitelisted-allowed number. If you want to download it from google play, it has a 'B' on a padlock icon. I change the call setting from "block private number" (hidden callerID) to allow "phonebook only" (only allow incoming calls from Contacts and Whitelist). It only works for Android version 4 or less. The latest embware version changed to a 10-second delay to open (demo) but seemingly fully-working version.