Once you've connected with investors and they've agreed to talk on the phone or follow-up with an email, your goal is to find out what "proof points" they would need to invest in you. Don't start pitching right away. Just tell them about your business and what stage you're at.
The goal of this task is to find out what you need to do to be "in the same ballpark" as companies they invest in. Tell them what milestone proof points you're working on and ask if they'd invest in a company that has achieved them. Then you know you'll have a "fundable company" once you reach that milestone.
It's important to start these discussions months before you actually need to raise money. If you're in the early idea stage, then talk to angels about the idea. If you've just raised angel money, start talking to VCs, strategic partners, or potential customers. The feedback will help align your team and builds a relationship in advance of needing it.