From a traveling agent leaving a code # who are these people?

Pickup no sound.

Nation Transport Travel Survey. It's related to a mail survey that we sent in a few weeks ago from the US Department of Transportation. The printed survey said they would call later for more information. I sent them to voicemail and they left a message.

So weird they called. I don't like surveys!

This is a legitimate government survey.  They wouldn't be calling you if you had not already given them your number from the paper survey they previously sent you.