RPX, which buys up patents to help companies reduce their risk of being sued for patent infringement, will make the purchase through its subsidiary, RPX Clearinghouse.
Rockstar originally bought around 6,000 patents from the Nortel bankruptcy sale for $4.5 billion.
About 2,000 of those patents were distributed among various consortium members and are not part of the sale to RPX.
RPX is contributing about US$35 million towards the deal.
The remainder of the costs are being covered by a syndicate of more than 30 companies, including Cisco and Google.
"This is the largest syndicate of its kind and it proves once again that our clearinghouse approach can transform the patent licensing process from one dominated by prolonged litigation to one that is transparent, scalable and provides a rational outcome for licensors and licensees alike," RPX co-founder and CEO John Amster said in a statement Tuesday.