What is this?

So I got a call from a strange number this morning asking about an insurance quote. I never solicited my information to anyone and I told them I didn't think they could beat my insurance rate anyways as it just went down to 121 a month for a 2012 dodge ram with full coverage and a 2015 leased Toyota Corolla s with full coverage and a 500,000 life insurance policy but they could try as long as I didn't have to give my information out. She stated they already had all that on file. I told her if she had my social security number it was illegally obtained and that she better not run it. Then she proceeded to tell me that they could get my social just from my birthday and address. I'm appalled that a company can get that information when you didn't give them permission. Sorry for the long post but my question is how can people do that, I'm aware that some companies solicit your information but I always read what the share and to who.