The decision was welcome news for RIM, which suffered a major setback earlier this week when a US judge invalidated its $450m settlement with NTP and rejected a request to delay the case until all final patent rulings.

The patent office found that the NTP’s wireless technology patent might have been first filed by a Norwegian company. The ruling, however, is preliminary and NTP will be allowed to respond to it. Moreover, it only covers one of five NTP patents RIM was found to have violated. Final rulings on the patents could take several months or even longer.

The court ruling earlier this week ordered a hearing to determine whether to block US service for the Blackberry and how much RIM should pay for the alleged infringement.

The decision sent RIM shares down 5.8% to $61.13 on Wednesday. But with the positive news from patent office, the stock had climbed back up to $64.50 by market close Friday.