Research In Motion Ltd., the maker of the phones, said the system was back to normal early Thursday. The outage interrupted email messages and Internet services.
The problems began in Europe but also impacted customers in the U.S.
BlackBerry advised customers who were disconnected from the network to pull out the phone's batteries and put them back in to reset the devices.
Officials say they have not made plans yet to compensate customers.
"That is something we plan to come back to these customers on very soon. ... Our priority right up until this moment (has been) making sure the system's up and running," co-CEO Jim Balsillie said. "We're going to fully commit to win that trust back."
The Associated Press contributed to this report.