Conference calls have become a great and inexpensive marketing tool. You are able to address more people in far less time than calling them individually. It's also done for much less cost in both time and money. A Buisnessknowhow article, Top-Ten Marketing & Sales Strategies
for a Slow Economy, has some very good advice. There is one tip however, that needs some elaboration.

The tip in "Strategy 4: Collect E-Mail Addresses" is a good one by itself. Email addresses are powerful communication and marketing tools. You can use them to keep your current and potential customers updated on your products and services, as well as let them know when something new comes out. Getting those email addresses from customers can be an easy part of your sales process. For non-customers, getting their email addresses takes a bit more creativity. A solid method is to trade information, samples, or minor services for their email.

There is another way that this tip can be used. Use a conference call registration page on your website when you whatever trade for emails. Then you not only have a list of potential people to approach for sales, you can use their emails to invite them to your conference calls.