There's a huge battle underway between Netflix and Blockbuster Video for subscribers who rent their DVD's by mail.

Netflix pioneered the concept and has 6.7 million customers. Blockbuster, with 3.6 million customers, is now experiencing faster growth with their Total Access plan that lets you get an extra DVD - in addition to the mail delivery - by exchanging it in the store. (An offer that is cannibalizing Blockbuster's store sales in order to boost the mail program.)

Still, it's advantage Blockbuster, right?

Well, Netflix has decided to change the rules too -- for customer service. According to the New York Times, Netflix shut down its e-mail customer service and opened a 24/7 toll-free call center, choosing live voices over keystrokes. This is no offshore outsourcing either; the call center is located in Portland, Oregon and staffed by lots of friendly people who are directed to take as much time as they need on the phone to handle customer concerns.

Experts say it's the exact opposite of what everyone else is doing in customer service. And that's good, because it's a Unique Selling Proposition (USP) that differentiates Netflix from Blockbuster.

This battle is far from over, but there's a lesson here for all of us. Having a USP that focuses on superior customer service may be a great defense against a competitor that's willing to lose money in order to beat you.