NTP Inc., a patent-holding company that won a $612.5 million settlement from RIM in 2006, has struck again with a settlement involving 13 of the biggest companies in the tech industry.

NTP, noting that it holds eight US patents "relating to the delivery of electronic mail over wireless systems," today said it reached a settlement with 13 companies representing just about everyone involved in building and selling smartphones or delivering e-mail to them. The 13 companies are AT&T, Verizon Wireless, Sprint Nextel, T-Mobile, Apple, HTC, Motorola Mobility, Palm, LG, Samsung, Google, Microsoft, and Yahoo.

"The signed agreement provides broad coverage under NTP’s patent portfolio to all of the companies," NTP said. Consequently, "all pending litigation between NTP and these companies will be dismissed."

With the exception of Nokia and RIM, who were already paying NTP, the settlement covered "pretty much the entire industry," said intellectual property attorney Ron Epstein, who was settlement counsel for NTP and used to run Intel's licensing group. But when asked if that means NTP is done filing lawsuits, Epstein told us there are a couple more companies in NTP's sights.

Terms of the agreement were not disclosed, but Epstein told Ars that the companies involved "were able to provide a financial return to patent owners that they're happy with and provide substantial discounts to each of the participating parties." He said the deal is unique in that it covered a large number of companies rather than just one, and happened somewhat independently of any lawsuit. Pending litigation had been stayed while the US Patent and Trademark Office re-examined NTP patents, he said.

NTP has been called a "patent troll," namely a company that makes no technology of its own but uses patents to sue others. While NTP doesn't make any of its own technology, Epstein said it was created with the intention of building technology, not suing. NTP was founded by Thomas Campana, who filed for and received dozens of patents before dying in 2004. One representative patent describes an "Electronic mail system with RF communications to mobile processors," and was awarded to Campana in 2001.

Epstein said NTP did try to make its own products in the early 1990s, but was too early. "NTP [and its predecessor company] was working on building systems to send e-mail over wireless systems in 1990, '91, and '92," Epstein said. "In that era, almost no one had e-mail, and cell phones were the size of brief cases. They were way too early. They were founded to become a product company, but they were founded way too early."

Epstein added that Campana and colleagues "demonstrated a working wireless e-mail system on AT&T's network in 1991."

Some of NTP's patented claims were invalidated upon being challenged in front of the US Patent and Trademark Office, but enough stood for NTP sue major smartphone makers in 2010. The company then won a US Court of Appeals ruling in 2011 upholding the validity of many of the patents that were previously called invalid by the US Patent Office. That favorable ruling likely helped NTP win the settlement it announced today.

While NTP's announcement stated that it holds eight patents related to wireless e-mail technology, the company has at least a couple dozen overall. Epstein said the licensing agreement gives the 13 companies coverage under NTP's entire patent portfolio, not just the eight patents referenced in the announcement.

We're trying to get confirmation from the companies involved in the settlement. So far, Microsoft has declined to comment.