This number appeared on my mobile phone display. I did not answer and they did not leave a voice message. The above callers received their calls today too. Spam!

Called my mobile phone, no message left on voicemail. Sounds similar to other calls I've received from different numbers which, when I called the number, answered with a recorded message that the survey I was calling about had ended. I've now added 415-906-2127 to other "survey" numbers I've blocked.