For mobile phone manufacturers, going green is not a new goal. For the last several years, the major handset makers like Nokia, Motorola and Samsung have been introducing greener practices and products. Doing so has proved expensive, but also increasingly necessary for brands wanting to stay competitive in a hot and crowded market.

Several factors are motivating this transition to sustainability. More national and global regulations are mandating eco-friendly products with stiff penalties for violators. In many ways, sustainable practices like enforced recycling are economically advantageous. And perhaps the most influential reason is that the public has started demanding greener products, making it a nearly non-optional marketing strategy.

Phone makers have done an impressive job responding to these market forces. In Greenpeace’s 2010 Guide to Greener Electronics, Nokia and Sony Ericsson won by a longshot, trailed by other honorees Motorola and Samsung. Clearly, going green has been a major priority, and these companies are on the right track.

Both Nokia and Sony Ericsson won their top spots by eliminating toxic chemicals from their products and supporting legislation to ban compounds — like chlorinated and brominated flame retardants — across the board. This has turned both companies into thought-leaders in corporate responsibility, enhancing their public image.

Some not-so-prescient manufacturers have hit a wall when it comes to toxic substances. There’s no better example of why this is important than what happened to Palm in the summer of 2006. That’s when the European Union’s Restrictions on Hazardous Substances kicked in, limiting the use of lead, mercury and other compounds. Palm’s Treo 650 smartphone didn’t comply with the new standards, and the company had to stop shipping to Europe. It lost an estimated $20 million and its share price plunged 14 percent. Since then, even more stringent regulations have been discussed, which will inevitably reward manufacturers that are ahead of the curve.

Toxic substances are closely tied to electronics recycling practices — another area ripe for legislation. In the U.S., states have already mobilized to limit what has become known as e-waste, a mounting problem worldwide as personal electronics become more pervasive. As a result, many handset makers have made it easier for device owners to recycle their products. This is especially important for cell phones, which are generally retired and replaced every two years.

Recycling mobile phones is not easy or cheap — with 80 percent of the cost of recycling attributed to the labor required to dissemble phones and sort the components. But they are doing it anyway in order to avoid falling behind the times and shrinking their prospective markets.

But these companies aren’t just playing defense. They are actively innovating to make their products greener — and more importantly, to make them easily perceived as greener by prospective customers. This demonstrates how important sustainability is as a marketing tool.

Both Nokia and Motorola have launched phones named to reflect their green leanings and have made a big deal out of building in small solar panels for charging on the go, and making phones out of recycled and biodegradable products. Both companies admit that these entrants are still geared toward a niche audience, but they predict the customer base to grow with time.

However, nothing is more indicative of how important this is to OEMs than their collaboration on a universal charging initiative. A couple of years ago, the world’s top five handset manufacturers (Nokia, Samsung, Sony Ericsson, LG and Motorola) joined together to start a rating system for mobile phone chargers. Chargers are assigned one to five stars based on how energy efficient they are.

So, while the natural assumption is that phone manufacturers won’t be able to afford going green in such an intensely competitive market, the truth is that they can’t afford not to.