The Digirit SIM+ case.
The Digirit SIM+, a case designed for the iPhone 5, houses two SIM cards with space for a third spare. Some nifty electronics connect both SIM cards to the iPhone's internal SIM card slot, and an app can switch between the two active SIMs at will.
Digirit's proposal for the SIM+ case is for its already-created prototypes to be refined and mass-produced: "Imagine an iPhone 5 that holds two SIM cards, letting you toggle between them easily, right within the Settings panel of your iPhone 5. The SIM+ is our solution. We'd like to make it a reality for everybody else too."
Dual-SIM phones are a niche market, but suit travelers and business users who keep the same phone for work and personal use. Digirit's app can even be set to switch SIM cards at a predefined time, so the iPhone can switch to personal usage at the end of a work day.
The Digirit case can use one micro-SIM and one nano-SIM simultaneously, with the storage space suiting an additional micro-SIM. The SIM+, currently seeking funding on HWTrek, has 24 days left to run on its US$40,000 goal, and has had a slow start; it has eight backers and a grand total of US$495 pledged.