Green Rankings: The Top 10

Sprint Nextel was the first U.S.-based wireless provider to announce a target for reducing its absolute greenhouse-gas emissions. The goal: reduce emissions by 15 percent between 2007 and 2017 by improving energy efficiency within its networks, and by using renewable energy sources, such as hydrogen fuel cells, to replace backup generators at its cell towers. The company boasts a portfolio of three environmentally friendly phones, which is unusual in the industry. It also has a well-known product-recycling program in which customers can return their old cell phones, batteries, and accessories, regardless of brand, to Sprint for free using a postage-paid label. In some cases, Sprint will even buy back old equipment. Their aim is to recycle 99 percent of products; as of 2009 they were recycling nearly half.

One of Sprint Samsung's green phones, above.