Who called from 5034571379

Same ... Answered and no one was there.

Answered & no one there

Spammer with no regard for the FCC Do not call list.

Same, no answer and when i called back it said server temporarily unavailable in some british accent

It was a recording that said that it was a political survey about "our nation's debt crisis".  I was puzzled because I am in Canada and the area code is US.  It said that if I participate in the survey I can enter to win a 2-day cruise.  I hung up.  Obviously some kind of scam.