Now it’s the turn of T-Mobile USA’s to step up to homeplate as they announce that subscribers will be able to purchase services and goods through their mobile phone account.

Similar to the recent announcement with Verizon and Amex, T-Mobile are offering carrier billing for a number of stores and items to their customers. Much like a credit card bill, items purchased through carrier billing on your phone will appear on a monthly bill, alongside call charges, data bandwidth, and the rest of the fun of the mobile monthly account.

It also means that transactions are going to be a lot easier to push through as credit card details will not need to be entered on the mobile screen, but simply applied to the next phone bill.

It’s good to see that T-Mobile are using the ISIS system, just as Verizon are using. A common system, much like email, will help adoption of a standard, and then the mobile networks can duke it out just as Visa, Mastercard and Amex do in the bespoke credit card marketplace.

Given that everyone pretty much grabs their phone before leaving the house, enabling it as a psuedo-credit card makes practical sense, but making sure that this ability is not dependant on using a specific network, but is available to all, is even more important. It would be like SMS text messages not being able to be sent from AT&T to Sprint, or Citibank unable to transfer money to RBS.

The value is not in being first or unique for the user, it’s about ubiquity and being everywhere, allowing people to be confident it will just work. Which is what appears to be happening.