New York City Real Estate Firm Coldwell Banker Hunt Kennedy spends 85% of its advertising budget on print ads. But 75% of home buyers begin their searches online. CEO David Michonski suspected for years that his firm was wasting ad dollars.

Last year, Michonski confirmed his hunch. Through a phone system, of all things.

The busy Coldwell Banker franchise, which sells about $1 billion worth of pricey real estate a year, installed a voice over IP (VoIP) phone system. Its IT director, Eric Bassa, with help from vendor M5 Networks Inc., developed an application that tracks inquiries from every ad. The firm use a different phone number on each ad, and because calls come in as converted IP data packets, software can tap into them.