Blackberry maker Research in Motion (RIM) scored a year-ending victory in its long- running patent dispute with NTP Friday.

But the future of operating its popular wireless e-mail service in the U.S. is still uncertain for the Canadian-based company, which faces the prospect of an injunction over patent litigation covering the technology.

According to the United States Patent and Trademark Office (USPTO), the agency issued a "non-final office action" on Friday rejecting two of NTP's patent claims against RIM.

USPTO spokesman Richard Mulsby stressed to internetnews.com that the decision is a preliminary one and that NTP has time to respond and challenge the ruling.

Nevertheless, the USPTO ruling is some of the only good news for RIM in the last several months.

In November, a federal court ruled the $450 million patent dispute settlement between RIM and NTP, a Virginia-based patent holding company, was invalid. The decision put NTP into a position to demand as much as $1 billion in settlement fees and a possible shut down of RIM's service in the United States.

NTP has long claimed the BlackBerry infringes on patents held by NTP. More than three years ago, a Virginia court ruled in NTP's favor and the two companies have been jockeying for legal advantage since then.

In March, the two companies reached a preliminary settlement, but talks fell through after that. RIM went back to court to enforce the preliminary settlement, which the court rejected as a non-binding agreement.

With court challenges largely exhausted, RIM is hoping for more decisions from the USPTO to invalidate NTP's claims against it.

RIM did not return calls for comment. NTP was unavailable for comment.