IBM recently sent a missive addressed to Twitter that attempts to settle assertions of infringement on at least three U.S. patents currently owned by the tech industry giant.

The main patents affected are (1) U.S. Patent No. 6,957,224, the efficient retrieval of URLs, (2) U.S. Patent No. 7,072,849, a method for presenting advertising in an interactive service, and (3) U.S. Patent No. 7,099,862, a programmatic discovery of common contacts.

IBM divulged the information at a time when Twitter raised IPO share estimates to $23-$25, a $6 increase from the previous estimate and a sign of confidence in strong turnouts despite accusations thrown against it.

The updated S-1 filing implies that Twitter is prepared to face the challenges, including the settlement IBM asks from the social network.

Twitter said it is confident to have justifications against the allegations, even though it cannot assure success to its defense or to reach a settlement in its favor.

The annotation shows up in the S-1 update that provides more reservations about the way copyrights, patents, trademarks, and trade secrets often become grounds for litigation.

Twitter admitted that patent lawsuits are not its specialty, and noted that several competitors have larger patent and IP portfolios, enough for them to sue Twitter because of its incapacity to take legal action against complainants and plaintiffs that sue for patent or IP infringement cases.

The company added that many “non-practicing entities” with patents and IP rights frequently try to put forward serous claims in order to

it writes, with a special flag for trolls: “In addition, various ‘non-practicing entities’ that own patents and other intellectual property rights often attempt to earn from tech companies.

As Twitter continues to change and expand its service into new territory, it cannot keep on hiding from the long tentacles of patent owners and IP right holders such as IBM.

The company said its future products and services may cross into areas that may be patented, copyrighted, or trademarked by the competition and non-practicing entities.

Twitter noted that some advertisers and partners require the company to recompense for some IP lawsuits filed against them, even though the standard terms and conditions for Promoted Products and public APIs lack compensation for IP claims against Twitter advertisers and partners

Patent and IP lawsuits may incur large payments for considerable damages to defend Twitter advertisers and partners.

IBM, among the largest patent owners in the tech industry, has yet to announce if it plans to file a lawsuit against Twitter.

Facebook already bought lots of IBM patents in the past to bolster its patent portfolio and perhaps to avoid the quandary Twitter is in.