If you have two mobile phone numbers and hate to carry around two devices, the smartphone case called Talkase may be for you.
Talkase from WirelessMe is a smartphone case that has its own GSM phone built into it.
As silly and unnecessary as this sounds, it does actually have a purpose. Since it comes with its own SIM card, you can use the mini phone to send and receive calls as well as text messages. This is beneficial for people with multiple phone numbers because they can control two numbers from one device.
You can also use the mini phone to receive calls from your main phone just like you would a Bluetooth headset. The mini phone could also act as an emergency backup phone when your main phone runs out of battery.
If you pledge at least $29 on Kickstarter, you can receive a Talkase to use on your iPhone or Android phone. The case may not be the best looking source of protection, but it does come with some interesting perks. It is available in black, white, blue and orange, and you can have your choice of colors based on how much money you pledge.