Research In Motion (RIM) admitted that the cause of Monday’s 3-hour BlackBerry service outage was an upgrade intended to increase capacity. In a statement explaining the cause of the outage, RIM said it was “a problem with an internal data routing system within the BlackBerry service infrastructure that had been recently upgraded.”

A similar explanation was given last April when another widespread outage occurred. Although network outages have been rare in RIM’s service history, BlackBerry users complain that outages are more than an inconvenience.