With mobile usage continuing to skyrocket, it’s no surprise that Microsoft’s search engine, Bing, is also looking at ways to ensure that the search results it delivers to mobile users are capable of delivering the information and answers they’re looking for.

Recently, it began displaying a “Mobile-friendly” tag to search results for sites that it determined provide reasonable mobile experiences.

In the coming months it will go beyond this, incorporating mobile-friendliness as a ranking factor. On the Bing blog, Shyam Jayasankar of the Bing Mobile Relevance Team explained:

Our approach to mobile friendliness as a ranking signal balances the need to improve the ranking for mobile-friendly pages, with the continued focus on delivering the most relevant results for a given query. This means that for mobile searches on Bing, you can always expect to see the most relevant results for a search query ranked higher, even if some of them are not mobile-friendly.

While the changes will improve ranking for mobile-friendly pages, webpages that are highly relevant to the given query that are not yet mobile-friendly will not get penalized. This is a fine balance and getting it right took a few iterations, but we believe we are now close.

According to the blog post, Bing is looking at a variety of factors to determine mobile-friendliness.

These include easy of navigation on touch-based devices, readability without zooming, lack of horizontal scrolling and device compatibility. The latter looks at the use of plugins, like Flash, that are problematic on many mobile devices.

In explaining these factors, Jayasankar compared a number of sites on mobile, showing how Fandango provides good mobile navigation while Movies.com does not, and how Wikipedia’s readability is superior to that of the REI website.

Of course, because Bing says it will still favor overall relevance for mobile search results, the search engine’s changes aren’t nearly as threatening to companies that don’t meet Bing’s mobile-friendliness standards. The world won’t end for them, at least overnight.

But that doesn’t mean that companies companies that aren’t well on their way to delivering excellent mobile experiences aren’t losing out when mobile users click through to their sites. When evaluating whether they’re succeeding on mobile, companies should not assume they’re doing okay simply because the top of the funnel hasn’t decreased in size.

Case in point: according to a BrightLocal survey, 61% of mobile users are more likely to contact a local business if it has a mobile site.

That number is only likely to increase over time as mobile usage continues to grow and consumers become more demanding, so companies need to closely monitor the entire funnel for evidence that their mobile strategies are or aren’t cutting it.