Who called from 2017437425

Didn't answer this unknown number they didn't leave a message I tried calling back got a busy signal

Got a missed call from them an hour ago, left no message, called back and got a busy signal.

Answered and a recorded message said they wanted to give a free GE home security system. Hung up.

Got a call from this number.  Did not recognize the number so I didn't answer.  Not sure how they can call when number is on DNC list.

The DNC is not a call blocking service. But here's a clue for you. No legitimate sales company will call you if you're on the DNC, unless they are returning your call. That tells you everything about your caller.