Entered my information on an insurance website as well.
I work in sales, so I knew what to expect. The person who is calling from this number has purchased "online leads" and they have it set up to automatically dial as soon as a telephone number is entered. (That's why when you answer the phone it sometimes seems like you've caught them by surprise)
Also made the mistake of giving my phone number while trying to get a health insurance quote. They wont stop calling. I blocked the numbers, but now they keep calling from an unknown number!