Research in Motion has settled its patent dispute with NTP.

The Blackberry maker has agreed to pay $612.5m which includes a perpetual license on the patents that were at the centre of a prolonged legal battle between the two. The judge presiding over the case was expected to rule in NTP's favour and order a shutdown of the wireless email service in North America.

"We are pleased to have reached an amicable settlement with RIM. We believe that the settlement is in the best interests of all parties, including the US Government and all other BlackBerry users in the United States," NTP co-founder Donal Stout said in a statement.

The two parties in March 2005 reached an agreement to settle the case for $450m, but that arrangement later fell apart.

A jury found in 2002 that RIM infringed on NTP-owned patents that cover an email system on mobile devices.

The US Patent and Trademark Office, meanwhile, has started to re-examine the NTP patents and has already invalidated several of them. A decision is on the remaining patents is expected soon, although the procedure could take years. A possible invalidation however won't affect the settlement.

Even though RIM faces the risk of spending money on a license for patents that could be invalidated, the lawsuit was scaring away customers and as a result had an impact on RIM's revenues, noted Kevin Burden, program manager for Mobile Devices and services at analyst firm IDC.

"This is probably money well spent. It's a boatload of money for patents that are likely not to be worth anything, but it's worth it if it removes the cloud over RIM's future," said Burden.