This "survey" crap is just a BS excuse to get around the do-not-call registry rules which exclude surveys. This is data gathering at best and bait-and-switch at worst. As others have said, any company that won't identify itself and won't leave a message is not legit and they know it. Have reported them at several other sites.
I've been getting calls from this number. At least 3 within the past week. They called again today (Sunday). I don't answer & they hang up when the answering machine picks up