Unwired Planet, formerly Openwave Systems, said in a regulatory filing today that it has received more than 1,900 patents, including 753 US patents, from Swedish telecom company Ericsson.

There's not much to Unwired Planet beyond its patents. The operating parts of Openwave were sold off before the transformation to Unwired last April. In September, Unwired launched patent suits against Apple [PDF] and Google, following a time-tested recipe: use patents on old, unsuccessful technology to ask for royalties on new, popular technology. It also had cases against Apple and RIM at the International Trade Commission, but dropped them in October.

It sounds like Ericsson isn't getting any cash up front in this deal—just a cut of the action from a company whose lawsuits may be just beginning, now that it has a trove of patents from Ericsson's big R&D operations.The agreement, noted earlier today by TechCrunch, calls for Ericsson to get 20 percent of any patent winnings up to $100 million, 50 percent of any gross revenue past that point, and 70 percent of revenue about $500 million (should they do that well.)

Unwired Planet has hired McKool Smith, a law firm that has been behind some of the biggest wins on behalf of patent holders in recent years; the firm spearheaded i4i's win against Microsoft, to take one example.

Openwave was a key player in creating early mobile browsers and in mid-2001 it dominated the market, with 97 percent of US mobile phones using some type of Openwave browser, according to Unwired Planet's complaint September [PDF]. "By July 2001 Openwave had increased in size to approximately 2,200 employees worldwide, and the company earned revenues of over $465 million for fiscal year 2001," Unwired's lawyers note.

Of course, the market wasn't that big compared to today. It wasn't until smartphones that comfortably read regular HTML Web pages came along that browsing the Web on a phone became truly popular, and Openwave's systems didn't really make it to the iPhone vs. Android world we live in now. In its lawsuit, Unwired Planet attributes Openwave's decline to "infringing competition."

Patent trolls going after cell phone companies are a dime a dozen these days, but Unwired Planet has good lawyers and a very serious batch of patents originating with once-innovative companies. Now that it's been anointed by Ericsson as its last-ditch patent enforcer, we'll probably be hearing from the company more.

This development comes several weeks after Ericsson, which hasn't been in the mobile phone business for some time now, filed its own patent lawsuit against Samsung. The Swedish telecom company also filed a patent suit against networking equipment makers D-Link, Netgear, and Gateway in 2010; that case is scheduled to go to trial in East Texas later this year.