Over the years I was contacted several times by VCs. Before giving out any information, I would sort out who exactly you are talking to. Often the people who call are headhunters of sorts. They are "associates" who are trying to get info. on your business. They are happy to take as much information as you will give them quite frankly.
Either way, I would ask more questions than answer quite frankly. Why are they calling? What interest do they have in your company? What companies do they invest in? What is the minimum revenue a company must have for them to actually consider an investment and how firm is that number?
You may find that based on the answers to these questions, there is no point in you divulging any information about your company.
I found that early on, I felt somewhat romanticized by VCs calling only to find out the people calling me were low level "grunts" of sorts milking me for info. I was overeager to share info. about my company.
As time passed, however, I became much more careful about what I shared and I generally was the one vetting them more than they were vetting me.