Millions of BlackBerry customers across four continents are without email, messaging and browsing service on their smartphones after a series of failures in Research In Motion's private network.

Extensive delays hit Europe, the Middle East, Africa and India on Monday and the problems spread to Brazil, Chile and Argentina on Tuesday in the latest headache for the Canadian smartphone maker.

The disruption piles pressures on RIM, which is fending off investor calls for a management shake-up and possible sale or split of the company as it shifts its phone lineup to new software first used in the widely panned PlayBook tablet.

The messaging and browsing delays being experienced ... were caused by a core switch failure within RIM's infrastructure, the company said in an emailed update late on Tuesday afternoon in Toronto.

RIM's BlackBerry service has long been prized by executives and politicians who rely on its security and reliability to deliver email and other messaging to mobile workers.

But problems with the service may hasten corporate moves to allow rivals such as Apple Inc's iPhone and iPad and devices running Google Inc's Android software to access data kept behind company firewalls, one analyst said.

The current situation with the BlackBerry outages couldn't come at a worse time for RIM, following some harsh criticism in recent months, Informa Telecoms & Media analyst Malik Saadi said in a statement.

Some businesses may see this as a good reason to reevaluate

their reliance on centralized servers and instead look to investing in more corporately controlled servers.

Not only would this enable IT departments to minimize the risk of unforeseen collapses, but it could also give employees more flexibility to use their own devices, he said.

The Canadian company manages its BlackBerry service via servers parked within enterprises and hooked up to a proprietary network carried by wireless operators.

Although the system is designed to failover to a back-up switch, the failover did not function as previously tested, RIM said. Failover refers to the automatic switching of service to a standby server in the case of a failure of a main system.

As a result, a large backlog of data was generated and we are now working to clear that backlog and restore normal service as quickly as possible, RIM noted.

RIM hosts a number of network operating centers, including one at its headquarters in Waterloo, Ontario, and another in southern England, which manage the massive amounts of data that flow through its system.

RIM has suffered outages before. Its BlackBerry Messenger service went offline in Canada and Latin America last month and a massive disruption hit North American customers in April 2007, but the disruptions are usually contained within one continent or region.

RIM has more than 70 million subscribers worldwide, with much growth in recent years coming from emerging markets.

At 10:25 p.m. Monday Eastern Time, RIM said it had resolved problems disrupting its services in Europe, the Middle East and Africa (EMEA). This was some 20 hours after users in EMEA and India first reported problems with email and BlackBerry Messenger.

In its latest update, RIM did not say when it expected the outage to be fully resolved or how many customers had been affected.

The outages are just another headache for RIM, which has less margin for error as rivals encroach on the corporate email market it once took for granted. Employees increasingly push to use their personal devices, typically iPhones and iPads and to a lesser extent Android devices, in the workplace.

It is also facing growing calls from investors for a break-up, sale or change of management following recent dismal results, slipping market share for its phones and a lacklustre reception for its PlayBook tablet, designed to challenge Apple's iPad.

Network operators and users in EMEA tweeted that email and BlackBerry Messenger services were not working from Monday morning in London. Network operator T-Mobile said on its website that the problems were due to a European-wide outage on the BlackBerry network.

It said: RIM has apologized for the interruption to services and said it's working to restore normal operations.

Vodafone sent a message to its British BlackBerry customers on Tuesday evening that noted you may still be experiencing issues with BlackBerry services and saying RIM was working to resolve this urgently.

(Additional reporting by Paul Sandle in London and Devidutta Tripathy in New Delhi; Editing by Will Waterman, David Holmes and Richard Chang)

Blackberry