Blackberry devices are used by three million people in the US

Canadian firm Research In Motion (RIM) reached a $612.5m (�349m) settlement with patent-holding firm NTP, averting the possible closure of its US service.

Despite the uncertainty, chairman Jim Balsillie said RIM had not lost any of its four million users.

He said that the settlement costs would be paid from RIM's $1.8bn cash pile.

The settlement brought to an end four years of legal disputes with NTP, which claimed that RIM's technology infringed on its patents.

Patent trolls

Although the US patent office had yet to issue a final ruling on whether the patents were valid, a jury found against RIM three years ago.

A judge in a US district court had threatened RIM with an injunction to block its US service if the two sides could not resolve the dispute out of court.

"I am not angry, but basically we took one for the team," Mr Balsillie told the BBC.

"The uncertainty was interrupting our business, so we made the sacrifice. But it is not something we feel all that good about."

Some experts have hit out at "patent troll" companies like NTP, saying they acquire and use patents just to sue companies that actually make products and generate revenue.

They are particularly unhappy that in such patent cases firms are able to obtain injunctions that can then threaten a company's entire business.

RIM boss Jim Balsillie said Blackberry customers stayed loyal

The Supreme Court is due to hear a similar case soon involving eBay and a patent-holding company called MercExchange.

"We feel the system has been manipulated," said Mr Balsillie.

"We shouldn't have to pay for the predictability of our business."

Looking forward, he said RIM had not lost ground to rivals like Nokia, Motorola and Microsoft.