I know someone, and he employed a professional company to canvass large companies by phone. They found out exactly who they needed to speak to, they then made calls to this person and found out if they where interested in a free quotation. All contacts were emailed to him after call. They would book the appointments everything, even the name of the operator that made the call. They had a 10% success rate on getting appointments, and 5% of those appointments turn into work.
But these were very big contracts, British Gas, Harvey Nichols and so on.