The maker of the BlackBerry smartphone confirmed on Monday that an outage had hit some of its services in Europe, the Middle East and Africa.
Canada-based Research in Motion said it was investigating the disruption that has led to many user reports of not being able to receive or send email, or use instant messaging, or being able to browse the Internet.
The problems did not appear to be the same for each user, or affect all users, according to Twitter messages about the BlackBerry.
"We are working to resolve an issue currently impacting some BlackBerry subscribers in Europe, Middle East and Africa," Research in Motion said in an emailed statement.
"We're investigating, and we apologise to our customers for any inconvenience caused whilst this is resolved."