This number has called my mobile phone the last three days in a row.  Never leaves a message and no caller ID except the phone #.  I'll give that # a couple more days and then I will block if they continue.

It's a independent research company calling for surveys.

Dont they have to respect the do not  call list?

Most survey calls are exempt from pre-screeening against the Do Not Call list. However, if the survey leads to a sales attempt, a request to have a salesperson call you, an invitation to attend a sales presentation, or an request to have someone stop by to give you an estimate, then the DNC rules apply.

Has called twice so far. I just let it go to voicemail...