Half of the top 20 most popular websites do not work well on mobile phones, even though up to 5 percent of visitors are now coming from mobile devices, according to a study conducted by Bango (AIM: BGO). It seems despite all the hype about the iPhone, most people are still using mass market phones from Nokia (NYSE: NOK), Samsung, Sony (NYSE: SNE) Ericsson (NSDQ: ERIC) and Motorola (NYSE: MOT). Bango, which provides tools for mobile analytics, said this continues to be an ongoing problem because most publishers don’t know how much traffic is coming from phones, but Bango’s research shows that between 3 to 10 percent “of on-line traffic to a PC website now comes from users entering web addresses on their mobile device.”

The tests were conducted on the Motorola V3 Razr and the Nokia 6400 on the AT&T (NYSE: T) network in the U.S. and Vodafone (NYSE: VOD) network in the U.K. Bango detailed some of the findings on its blog:

—Good experiences were qualified by sites that typically identified that the user was coming from mobile, and displayed information appropriately. The sites included: eBay; YouTube; AOL; MSN; Yahoo; Google; Amazon; Weather.com; Facebook and CNN.

—Bad experiences commonly returned a page view error, or didn’t interpret the content to make it easy-to-use on the phone. They included: Fox; Microsoft; Wikipedia; Apple; About.com; Blogger.com; RealNetworks.com; Glam Media; Craigslist.org.