Some ideas are so simple and effective that you wonder why they haven't been thought of before. One such example is the SpareOne phone that Pocket-lint got up close and personal with in Barcelona at MWC.

Xpal Power (the company behind Energizer and PowerSkin) had the SpareOne on show at the Spanish mobile expo, a month or so after going live with the official launch details.

Basically, the SpareOne is about as dumb a phone as you can imagine but could end up being a real life saver. The idea is that, powered by a lithium Energizer battery and devoid of any power-draining complications, the handset has a battery life of 15 years with 10 hours of talk-time.

The idea is that the SparePhone can sit in your glovebox, handbag or bed-side cabinet and be used whenever your regular mobile phone is dead and you have no way of charging it.

Simply pop in your SIM (or have a PAYG SIM ready loaded) and away you go. The SpareOne also cleverly packs a micro-SIM adaptor if you're using the smaller SIM-version and the pin required to pop a micro-SIM out of an iPhone. These are stored safely inside the back panel so there's no chance that you'll lose them.

The battery sits where the traditional mobile phone display would and the only input method is a numerical dialpad. There's no on screen display or phonebook, however there are 9 pre-set speed dial buttons.You can also use the red button to call the emergency services, even without a SIM loaded into it. There's even a torch on board should you be stranded in the dark.

There are two versions of the SpareOne coming to market later this month; a GSM 850/1900MHz for the States and a a GSM 900/1800MHz for Europe, Africa, Asia and the land down under.

While it feels slightly plasticy, it's not really intended as a high-end fashion statement. With the ridged back it's comfy enough to hold, it's extremely easy to take off the back panel and, at just 75g, it isn't likely to be too much of a strain in a bag or coat pocket.

The SpareOne phone is a brilliant idea and we're sure it'll sell by the bucket load when it starts shipping on 15 March. In the UK it will cost £59.99, it's $70 Stateside. You can order from www.spareonephone.com.