Most cell phone chargers today do not offer energy efficiency, as the charger usually heats up when the phone is receiving electricity, or when the battery is finally full. This wastes energy, and usually costs the consumer more on their energy bill than what they already pay. AT&T is looking to change this with their Zero cell phone charger, which cuts off energy to the device when the phone is disconnected. The product features a USB interface, so that almost any charger can be used to make those battery bars fill up on any phone. There is currently not a price or release date set for the AT&T Zero, and it is not yet known either how much energy will be able to be saved overall.