Second, only raise money when you're ready to raise money. I'd make it clear from the start that you're not raising at the moment so the VC doesn't interpret your conversation as a week pitch. Tell the VC that when you're starting your fundraising process you'll naturally get in touch with them.

Third, who's actually calling? Is this a partner or is this an associate? Associates are often just gathering information about areas they think might be interesting - they're just looking to get educated / educate their firm, and they figure you'll be willing to help them out for free. Sometimes associates are doing due diligence on a potential investment by calling up competitors and seeing if they say the same things about the market.

In general, the conversation won't be that technical. They'll want to understand what you do at a high level, get your opinion on the size of the market you're in, figure out if you're going to need to raise, figure out how you're making money / plan to make money, etc. Don't feel compelled to tell them anything you wouldn't be comfortable telling everybody.

Also, it's a two-way street! Ask them a ton of questions about what they're doing, which companies they've been looking at, what they think of your market, who they think your competitors are, what challenges they think you'll face - take everything said with a grain of salt, since you know your business better than they do, but sometimes you can glean interesting bits of information that way.