What's the best way to cold-call executives?

Tim Ferriss wrote in The Four-Hour Workweek that he had the most success reaching execs after hours because their secretaries were gone for the day, FWIW.

It’s a numbers game—the more people you call the more likely you are to make a sale. Be persistent, direct and sensitive to their time. For your highest level targets I would avoid cold-calling and try old fashion approaches: send a brief handwritten personal note introducing yourself and mentioning that you will be following up with a phone call in a week. But at the end of the day, the best route will be your network and personal introductions—ask your family and friends, etc about links/relationships with your senior exec targets. That’s how business gets done.

My job is to make sure solicitation calls do not get to the big bosses. After hours calling is the best idea.