Microsoft's instant messaging service Skype has had its service disrupted by what its support team has described as “connectivity issues”.
The outage began on Monday, 19th June at 19:01 GMT.
Multiple countries are said to be affected, and Skype has published a blog on the topic.
Jagadish Harihara writes: "We are aware of an incident where users will either lose connectivity to the application or may be unable to send or receive messages. Some users will be unable to see a black bar that indicates that a group call is ongoing, and longer delays in adding users to their buddy list."
Dr Malcolm Murphy, technology director at Infoblox said in a statement: “In order to have a hope of successfully combating an extremely targeted DDoS attack companies need to be able to spot malicious traffic immediately. Despite the increasing amount of DDoS attacks it seems that very few businesses keep a regular check on DNS traffic or maintain detailed audit trails for DNS lookups."