Research in Motion co-CEOs Mike Lazaridis and Jim Balsillie held a phone press conference Thursday to announce that BlackBerry services have been restored globally after several days of network failure.

The pair apologized for the inconvenience the outages caused BlackBerry users worldwide but didn't answer any questions about compensating customers for the blackout that took days to fix.

"Our focus has been 100 percent on getting systems up and running," Balsillie said, adding that the company would look at other ways to compensate its customers.

"I want to apologize to all the BlackBerry users we let down," said Lazaridis. "Our inability to quickly fix this has been frustrating."

The blackout was caused by a failure in one of the company's data switches in Europe. The backup switch also failed, creating a backlog of e-mails and messages that caused a shutdown in Europe, Africa and the Middle East. The problem ballooned to outages in other RIM data centers around the world.

"We don't know why the switch failed in the particular way it did," said Lazaridis.

The two chiefs explained that the switches came from several manufacturers but wouldn't name them. Lazaridis said RIM would be checking its infrastructure to determine the cause of the failure and would be working with the hardware manufacturers to prevent the same problem from happening again.

The outage, the largest in RIM's history, caused significant headaches for its users who rely on the company's closed network to send e-mails and text messages. Executives around the world, RIM's core market, were particularly exasperated with the company's lack of communication with users and carriers about the outage.

"The communication from RIM could have been more proactive," said Julia Buchner, a spokeswoman for chemical firm BASF SE in Germany.

The two CEOs admitted that the outage had caused their customers to lose confidence in the company.

"We've worked 12 years since the launch of BlackBerry to win the trust of our users, and we're going to work hard to win that trust back," said Lazaridis.