MShift Inc. has filed a patent infringement lawsuit alleging that Intuit Inc. is using its mobile banking technology.

The 881 Patent, "System for Converting Wireless Communications for a Mobile Device," was awarded to MShift by the U.S. Patent Office in 2005.

It allows smart phones and other mobile devices to access network sites using a conversion engine that translates the language of the network site (HTML, for example) and the language of the mobile device (HTML, HDML or WAP).

MShift, which announced the lawsuit Feb. 19, was one of the first companies to offer mobile banking software.

Intuit's Digital Insight Corp. initially signed a referral agreement with MShift and later became a reseller. But that relationship ended in late 2009 and Digital Insight has started working with another mobile banking technology vendor.

"They're selling a competitor's technology that directly infringes on our patent," Scott Moeller, MShift's chief executive, said in an interview last week. "It's crucial at this time that we really protect our technology and not let people steal it."

MShift, of Fremont, Calif., filed the suit in United States District Court for the Northern District of California.

Intuit's new partner is Mobile Money Ventures, a joint venture of Citigroup Inc. and the South Korean wireless carrier SK Telecom, which was not named in the lawsuit.

Moeller said the venture may be added as a defendant in the case later.

The MShift technology has been especially popular with credit unions; Moeller said 28 of the 50 largest credit unions are offering mobile banking services and 18 of those are using software from MShift.

Representatives of Intuit, of Mountain View, Calif., did not return calls. Intuit acquired Digital Insight, a provider of online banking software, in February of 2007.

MShift has applied for a patent that enables deposit transactions on all smart phones, including Research in Motion Ltd.'s BlackBerrys, Apple Inc.'s iPhones, models from Nokia Corp. and handsets using Google Inc.'s Android operating system.