Four of the greatest inventions of my lifetime are ATMs, EZpass, cellphones, and subscription music. Three of these inventions have adopted roaming and the other one needs to.

When I first used an ATM in the late 70s, you had to find an ATM for your bank. But soon there were networks like Cirrus that allowed you to "roam" to any ATM and pay a small charge. That made life so much easier.

The same thing happened with cellular phones. When I landed in Venice last month, my blackberry immediately connected to some italian wireless phone company and I was in business.

EZpass, the prepaid toll system we use here in New York, is an amazing thing. I never wait in line at the toll booth anymore. And when I drive in New Jersey, their automated toll system recognizes my EZPass and lets my through in the fast lane.

But that’s not how it works with subscription music. Some people use Napster. Some use Rhapsody. Some use Yahoo Music. I think these services should get together and let their users "roam" onto other networks. Let’s say my brother uses Napster and he wants to send me a link to a song by Gomez. He sends me a Napster link and I can’t listen. But I should be able to do that. Either translate that link to a Rhapsody link or let me log into Napster using my Rhapsody account.

ATMs, cellphones, and automated toll systems have shown that by being open everyone wins. The subscription music services should take a page from their playbook and do the same.