"Our inability to quickly fix this has been frustrating," Lazaridis said after three days of intermittent service for text messages and e-mail.
On Monday, the problem was hardware. A "redundant-core switch" that protects the phone's infrastructure failed, disrupting text messages and e-mails in India, Africa, the Middle East, Europe and parts of South America, CNET said.
The switch first failed in Europe, and when the backup plan failed, the problem spread around the globe.
"We plan to come to customers on this and make things right with them," Lazaridis said.
Balsillie said system breakdowns were still few and far between. Although admitting the company let its customers down, he said the average downtime per year for the past 18 months has been 160 minutes per year.