Mobile phone sales plummeted in the first quarter of 2009, and a new Pew Research report released last week, says one-third of 18-29 year olds have changed cell phone plans as a result of the recession, a higher rate of change that was seen for any other age group.

These changes are likely to have the greatest impact on T-Mobile. Not only is T-Mobile the #4 U.S. provider behind AT&T, Sprint/Nextel and Verizon in both size and spending, it is also the only provider that skews significantly younger; 33% of 18-24year olds claim to have used T-Mobile compared to just 22% of the total population (Mintel, August 2008). With so many accounts in play, I thought it would be worth looking at what T-Mobile is doing to reach Millennials.

The most visible effort is the video of the “T-Mobile dance” stunt created in Liverpool’s train station in January (see above). A second stunt April 30 featured 13,000 karaoke singers in Trafalgar Square last month. The spots have a great tagline – “Life is for Sharing” – and were a viral web sensation. The Life is for Sharing YouTube channel continues to bring in traffic and videos. Adrienne Waldo’s provides a great Millennial view on this campaign in her blog, Ask A Millennial.

This is what happens when a company puts a little thought, effort, money and heart into their marketing. They are getting hundreds of thousands of views a week and sitting solidly at the top of AdAge’s Viral Video Chart. People are watching these videos over and over and sharing the gospel – blogging, tweeting, posting, forwarding and linking these videos into every nook and cranny of the web.

What did T-Mobile do differently from the countless other brands trying to infiltrate the masses virally? They abandoned the stereotypes of “savvy internet users,” realized that the people who use the internet are humans, and created their ads accordingly. I also have to give them mad props for their excellent song choices. Bang up job, T-Mobile, cheers and all that. Now, if only your service was as good as your marketing…

To see a great commercial inspired by the T-Mobile effort, watch this spot filmed in Antwerp, Brussels that features Julie Andrews singing Do Re Mi (don’t ask, just watch it.)

I took a look at some of their marketing and was very impressed. Beyond a great branding effort, T-Mobile is addressing the current cost consciousness by directing customers and prospects to a third party site, BillShrink.com for a Mobile Makeover. By entering basic information on usage and rates, you can see if there’s a way to do better on your cell phone bill. This seems risky unless you actually do offer better rates. I found the T-Mobile web site very intuitive and easy to use, in contrast to others I have visited. Finally, a quick check of JD Power shows customer service at T-Mobile is a strength: JD Power put T-Mobile first in customer satisfaction in its report, primarily due to shorter wait times.

Now let’s just hope that the rumors that T-Mobiles servers were hacked over the weekend are not true! It would be a shame given their overall great marketing effort.