Microsoft appears to be preparing to offer its own SIM card, that tiny electronic device that slips into a tablet or smartphone, letting you access wide-area wireless networks operated by the big telecom companies.

As first spotted by The Verge, Microsoft has added a "Cellular Data" app to its Windows app store that "allows you to connect to a trusted nationwide mobile data network." According to the app's description, it requires a "Microsoft SIM." This could mean any number of things, and Microsoft has yet to comment. But a Microsoft SIM would be another indication of the gradual power shift that's remaking the world of wireless.

Over the past year, the power in mobile has shifted away from network operators like Verizon and AT&T and toward device makers like Apple and Google. In the process, most importantly, power is shifting into the hands of consumers.

A Microsoft SIM would push the carrier into the background and put the Microsoft name front and center.

In the past, in order to use a cellular network in the US, you typically needed a SIM card from one of the major operators and a contract that locked you into that network for a good two years. Carriers would subsidize phone purchases in order to lock you in. But now, smaller carriers like T-Mobile are offering access without extended contacts. More importantly, device makers like Apple and Google are building the hardware and software the world really wants—and they're building those devices to more easily free users from the tyranny of a single carrier. And the carriers, thanks to consumer demand, can't shun Apple or Google. They have no choice but to play along as their old business model crumbles.

Today you can buy phones directly from device makers on an installment plan, while Apple and Google have started to offer SIM cards that let you more easily move between carriers. With its iPad tablet, Apple offers a SIM that lets you test and choose from a list of carriers—and sometimes switch between them. Google has gone a step further with Project Fi, which provides a SIM that will automatically move you between different networks, depending on which signal is the best.

Yes, these efforts still have their limits. Apple's SIM doesn't work with Verizon. Project Fi only works with T-Mobile and Sprint. But we're slowly moving towards a world where the carrier sits in the background, where you can freely move between networks whenever it makes the most sense.

With its SIM, Microsoft could be trying something similar. The SIM may work behind the scenes with only one carrier—in which case, it's less interesting. But given the direction of the mobile business as a whole, it may well work with multiple carriers (though the SIM is apparently for use with tablets like the Surface rather than smartphones).

At the very least, a Microsoft SIM would push the name of the carrier into the background and put the Microsoft name front and center. Once again, the carrier fades into the background.