Japan’s NTT Docomo has hit upon an interesting idea: a wearable SIM card that can connect all of your devices to the net via a single account.

According to Docomo, the wearable SIM isn’t ready to go to market yet. It’s prototype is described as a “pocketsize mini device”, thought it’s promising further downsizing in future that will lead to a “convenient wearable device.” This device will come with a SIM card slot, NFC and Bluetooth functionality, reports IDG News.

Here’s what Docomo says about the device:

“By simply waving Portable SIM next to a mobile device, the user’s subscriber identity can be transmitted to the mobile device via Bluetooth, eliminating the need to physically insert a SIM card. Using this feature, for example, the smartphone user can switch their subscriber identity from a personal device to a shared tablet in the workplace. For security, the switched phone number in the smartphone is locked once the Bluetooth link is broken.”

Docomo says its portable SIM can also store multiple credentials like passwords and IDs, which means it can be used with a PC or other device. This would eliminate the need to constantly login to different websites.

The idea sounds like a good one. After all, lots of people use more than one device and this generally means having two or more SIM cards plus mobile data plans. Meanwhile, NFC is also becoming a common way to authenticate and initiate Bluetooth connections.

Multiple data plans are certainly not convenient, and neither are they cost-effective. Moreover, any technology that can improve security is a welcome addition.

For now, Docomo is focused on studying the “key technologies, functions and service applications before commercialization of the device”. It also says it’s going to study “ways to link Portable SIM and other smart devices, such as TVs, music players and in-car informatics systems, to bring convenient services and products to customers.”

Docomo hasn’t said when its device might be launched in Japan. As far as international sales go, this is a possibility, though the company says it will discuss the idea at international standards forums first.

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