Verizon, AT&T, and T-Mobile support Isis and in the past these companies have blocked access to Google Wallet.
The new Google Nexus 5 breaks free from carrier restrictions with improved usability of Google Wallet, but is still a limited system.
There is hope that Isis will be the mobile payment/wallet solution for many people and today is available for selected Android smartphones. You need to select your carrier on the Isis website to see which phones are supported.
As stated on the Isis site, "the Isis Mobile Wallet requires an Enhanced SIM card with Secure Element to store sensitive payment information. If your phone doesn't have an Enhanced SIM card, you will see an alert message during the installation process with a link to get one from your carrier." If you recently purchased an Android phone, it may already have an Isis-enhanced SIM card and the ones I have seen have Isis right on the card.
CNET reports that Isis will eventually come to the iPhone, but that likely won't happen until sometime next year when, and if, Apple releases an iPhone with NFC inside since NFC is a requirement for the system.
In addition to using your connected credit card or bank account, Isis is offering several incentive free offers to generate customers for the system. Coke is giving away free drinks in some vending machines and Jamba Juice is giving away 1 million free smoothies. Even better, purchases made through an American Express Serve account are eligible for a 20 percent discount, up to $200.
I may have to visit my local T-Mobile store and get my SIM back into my HTC One to test this out soon.