-By Mike Shields, Mediaweek

NEW YORK Mobile Internet usage is exhibiting healthy growth in 2008. More Americans are purchasing Web-friendly phones and consuming more online content overall, particularly material outside carriers' "walled-garden" environments.

That's according to a new report issued by mobile technology vendor Crisp Wireless, which claims that the total number of mobile Web impressions generated by users surged 29.5 percent in the second quarter of this year versus the previous quarter.

The estimate is derived from data compiled by Crisp's Wireless Publisher Network, which includes partners ranging from NBC to Hearst to Turner, which in aggregate reach 17 million mobile users each month.

Of course, the mobile Internet is still in it's infancy -- Nielsen estimates that 40 million U.S. users accessed the mobile Web last May, while there are at least 200 million wireless subscribers in the country.

But Crisp found that as the existing mobile Web user base grows more experienced, it relies less on individual carrier's prepackaged Web portals -- known as "decks" in mobile circles. Many publishers for traffic growth see positioning on decks as crucial in the medium's early stages.

However, on-deck traffic is declining steadily, according to Crisp's research. For sites that maintain both on- and off-deck presences, the percentage of traffic derived from on-deck exposure declined from about 54 percent in the first quarter of this year to almost 46 percent in the second quarter, said the report.