Frankly, the right answer depends a lot on the nature of the business, and the people involved.
Being in the tech business, I would never even consider hearing someone out on the phone, simply because >99% of the unsolicited phone calls we get are scams or completely inappropriate for what we do.
If you were to send me a personal email, OTOH, you'd be guaranteed a reply. And it'd be much more likely to be positive if I've had the chance to check out your offering at my own pace.
