The maker of the Blackberry wireless e-mail device says an insufficiently tested software upgrade was the cause of this week's network failure.
The Blackberry is often relied on to access e-mails
Blackberry's US and North American users lost their service on Tuesday and Wednesday as a result of the problem.
Research In Motion (RIM) said it was now looking to improve its testing and recovery processes to prevent such an outage happening again.
There are about eight million Blackberry users around the world.
Blackberry said in a statement that the failure was trigged by "the introduction of a new, non-critical system routine" designed to increase the system's e-mail holding space.
It admitted that "the pre-testing of the system routine proved to be insufficient".
RIM added that the process designed to maintain the service in the event of a failure "did not fully perform to its expectations", causing a longer delay before the system was restored.
Analysts said they did not expect the outage to affect the Blackberry's popularity.
"So long as RIM solves whatever went wrong and communicates it well enough to customers, we foresee no lasting impact," said D Newcrest analyst Chris Umiastowski.
It is estimated that RIM has around 45% of the market for smart phones.
Preliminary figures recently showed that the firm's profits jumped tenfold to $187m (£94m) in the three months to 3 March.
The network disruption comes as RIM faces a formal probe by the US financial watchdog, the Securities and Exchange Commission, over its stock options.