It was not immediately clear how many of the 12 million worldwide BlackBerry subscribers had problems, as some users reported being able to access their service normally Monday afternoon.
But Garth Turner, a member of the Canadian Parliament, said during a caucus meeting that the incident's impact couldn't be overestimated.
"Everyone's in crisis because they're all picking away at their BlackBerrys and nothing's happening," Turner said. "It's almost like cutting the phone cables or a total collapse in telegraph lines a century ago. It just isolates people in a way that's quite phenomenal."
Bell Canada spokesman Jason Laszlo said the majority of their BlackBerry customers are affected.
"There's really no estimated time of repair," Laszlo said.
The BlackBerry service, which lets users check e-mail and access other data services on their handheld devices, has become a lifeline for many business executives and is increasingly popular among consumers with models like the BlackBerry Pearl.
In a statement, RIM said a "data service interruption" was resulting in "intermittent service delays for BlackBerry subscribers in North America." The company said voice and text messaging services were not affected.
A technical support recording for Canadian wireless provider Rogers Communications Inc. said subscribers could have difficulties sending and receiving messages, activating accounts and using other services like Internet browsing.
The company is "working with our vendor to resolve this issue," the recording said.
There was no word what caused the outage or when service would be restored.
Major disruptions have been rare but often provoke an angry backlash against the Canadian company because of its typically lengthy silences about the cause and because it eventually gives only cryptic, jargon-laden explanations.
When the BlackBerry service suffered a major outage last April, the company remained silent about the cause for two days.
The latest outage enraged some BlackBerry customers who were also hit by the network failure last year.
Stuart Gold, a customer who says he gets 1,000 e-mails a day as director of field marketing for Web analytics company Omniture Inc., worked on his laptop most of Monday after his BlackBerry went on the blink.
Although Gold said he thought last year's outage gave him a needed break from work, Monday's frayed his last nerve.
"I cannot believe this happened again," he said as he got off a plane Monday. "I'm on the road 300 days a year. My entire life is in my BlackBerry - my family life, my professional life, my emotional life, everything. ... They're not allowed to do this to me."
Gold, 49, said he plans to ask his company to buy him a second smart phone from a rival as a backup. BlackBerry competitors include Palm Inc.'s Treo.
In a statement, AT&T spokesman Fletcher Cook said the company first learned about the problem from RIM at about 3:30 p.m. EST.
"This is not an issue with AT&T's wireless network," Cook said. "Customers could experience difficulties using their BlackBerry devices. RIM has not given us an estimated time of when this problem would be fixed."
RIM is based on Waterloo, Ontario, and has deals with scores of wireless carriers to offer the BlackBerry service around the world.
