ZigBee searches for a new home
Squeezed into a SIM chip
The ZigBee Alliance has published a guide to using the standard in telecommunications, based around fitting a ZigBee node inside a SIM chip.
ZigBee Telecom Services is one of a handful of new additions to the standard, including healthcare and smart metering, but the guide (pdf ) is entirely based on the idea of fitting a ZigBee radio into a standard GSM SIM, something that Telecom Italia promised to show us in 2006 - and we're still waiting.
The idea is sound. Getting ZigBee into a SIM would provide compatibility with billions of GSM handsets, users could interact through the SIM Toolkit and the phone could be used for home automation, financial transactions and so forth. It could also encourage TV/AV manufacturers to adopt the standard for remote controls, if they could offer instant compatibility with every phone on the market.
SIMs have a standard interface system, known as the SIM Toolkit, which allows applications executed on the SIM to present a text-menu interface to the user on just about any GSM handset. Smartphones can replace that text interface with something prettier, but communicate with the SIM over the same mechanism. A ZigBee-equipped SIM could therefore control one's TV or heating using any phone with an interface commensurate to the handset, assuming one's TV and heating are ZigBee-equipped.
Which they aren't.
Despite knocking around for years ZigBee remains an industrial product used in vertical markets. Partly that's because it's a solution looking for a problem, but partly because competing standards muddy the water too much for manufacturers of white goods to make a leap into wireless.
Competing standard Z-Wave is more tightly controlled, to ensure interoperability. Today you can buy Z-Wave controllers, light switches and plug sockets, while the only ZigBee kit to cross the El Reg desk, ever was a home automation rig from AlertMe.com - now being pitched as a carbon-reduction technology rather than wireless networking.
But getting ZigBee into a SIM would make the technology much more accessible. RF SIM  and SIMFi  have both demonstrated it's possible to maintain a 2.4GHz connection from within a mobile phone, so the Z-SIM should be a lot more practical than it was when Telecom Italia first announced it, and the ZigBee Telecom Services spec is entirely reliant on the existence of such a thing.
Just to be sure, we asked the ZigBee Alliance for a demonstration of a Z-SIM, only to be told that we'd have to speak to Telecom Italia. We explained that we'd already been waiting four years and were told that a contact would be forthcoming - but we haven't heard back yet.
ZigBee on a SIM really is a good idea, but announcing it every five years is no way to inspire confidence when the competition is already on the shelves. Until we've held a Z-SIM in our hands we'll reserve judgement, and we'll be sure to let you know when or if that happens. ®