If you're smart, you're probably already saving money by buying used cell phones. Used cell phones come at a fraction of the price as new must have cell phones, while still maintaining similar quality. Plus, buying used cell phones extends the life of used cell phones, and saves the environment (be sure to recycle used cell phones when you're done!).

Now, apps are offering new ways to save money with your used cell phones. Lockmakers are making apps that will let you control the lock to your home, replacing your bulky keys. How does this save you money? They aren't just wiring your front door to your cell phone, their wiring the electricity, the air conditioning, and heating. Worried that a cell phone used this way is a security risk? Well, you can use cell phones to monitor security cameras and other devices, too! One hotel even used cell phones to replace room keys, so now waste created by over-circulated, stolen or damaged keycards will be reduced.

So if your away, use your cell phone to turn down your energy consumption, make sure everything's A-Ok, and save yourself some money on that bill. Or let a friend or relative into your house to feed your cat!

Soon, cell phones may also replace the lock on your car. Whereas replacing car keys can cost hundreds of dollars, replacing your cell phone is comparatively cheap, especially when you buy used cell phones. Not to mention, used cell phones are affordable and can easily be bought as a back up (in case a cell phone loses charge, is unexpectedly lost or broken, etc.). Comparatively, losing (or having stolen) and then resecuring and replacing a lock and key can get pricey, without including the time or stress the trouble causes!