It is interesting to read some of the early writings on IDX, commonly called Broker Reciprocity. Try http://BrokerReciprocity.InternetCrusade.com

For example, there is good background information from Brian Larson on the early days of IDX

http://brokerreciprocity.internetcrusade.com/web/BNLCommentaryonNAR.pdf

Brian says: "The telephone metaphor is useful here: When a buyer calls a broker on the phone to look at a listing of another broker, the showing broker does not respond by saying, Sure, I can show you that listing, but first let me tell you a little about the listing broker… Since the showing broker here EARNED the telephone call, she gets the opportunity to sell her services to the buyer, even though she is using inventory of other brokers to sell that service. The same is true in IDX. The site-sponsoring broker earns the consumer contact, either by advertising or relationship-building. Once the consumer gets to the sitesponsoring brokers web site, no one should force the site sponsoring broker to push that consumer away to the listing broker."

Saul