Nokia has sold off part of its massive patent portfolio on wireless technology to Sisvel International, a European firm that manages licenses on several technology standards including CDMA2000 and MPEG audio.

Sisvel bought 450 patents and patent applications for an undisclosed sum. The deal includes about 350 patents that Nokia has "declared essential" to telecommunications standards GSM, UMTS/WCDMA and LTE. The rest of the portfolio is comprised of "implementation" patents including video optimization.

Nokia is still licensed under the portfolio as part of the deal, suggesting it will not have to pay Sisvel to access the divested patents.

"Acquiring the many essential patents in this key portfolio is a very significant step for Sisvel," CEO Giustino de Sanctis said in a statement.

Sisvel did not say how much a license to Nokia's patents would cost, but de Sanctis said the portfolio would be offered on "FRAND terms" - fair, reasonable and non-discriminatory.

Nokia still holds more than 30,000 patents and patent applications, it said.

Intellectual property is a strong point for Nokia, which was able to make Apple sign a patent license agreement last summer that put an end to competing lawsuits before the U.S. International Trade Commission.

The Finnish handset maker raked in almost $640 million in licensing fees from its patents during the second and third quarter of last year, according to its financial statements.

Patents are hugely important to the wireless industry, with Google forking out $12.5 billion to get its hands on Motorola Mobility's portfolio of 12,000 patents. Motorola's intellectual property holdings will provide Google with legal ammunition to protect its Android operating system, which has been beset with a number of costly lawsuits over patent infringement.

Ericsson announced yesterday that it had decided to "strengthen its focus" on patent licensing. The infrastructure vendor has 27,000 patents on technologies ranging from 2G and 3G to WLAN. "Any company using cellular connectivity needs a license," Ericsson said.

Kasim Alfalahi, Ericsson's top executive handling intellectual property, is heading the initiative.