Of course calls for information interviews are not illegal. Information interviews are an important part of a successful person's job hunt or any target market research.
You will find far more people will be open to this than you think now. Some just want to be helpful. Others want to show off how much they know. Either way, they'll be gratified you called.
Here's a blog post I wrote about information interviews:
If someone says No, they're just too busy or they don't have the kind of personality you'd want to be around anyway. But far more people will say Yes. This is all about them--not you. Remember that.
Telemarketing laws pertain to B2C - Business to Consumer calls. http://www.consumer.ftc.gov/articles/0198-telemarketing-sales-rule
What you are doing is a fact-finding call to gather research. There is an art to doing this effectively and ending up with a sale.
If you would like to chat further, schedule a free call. See my profile for a promo code.
I don't think it's illegal in any jurisdiction that I'm aware of, but it may also not be successful.
Are you looking to get employment or sell something to them, or something else?
The best way to approach them depends probably depends on what you're looking to accomplish.