Microsoft Corp.-owned messaging service Skype suffered a serious outage Tuesday that affected users across the United States, Europe and parts of Asia.

The cause of the outage has not been officially revealed. Skype said only that it was aware “of an incident where users will either lose connectivity to the application or may be unable to send or receive messages.” But others suggested that the popular service may have been taken down intentionally by cybercriminals.

CNet’s Spanish language site claims that Skype was brought down by distributed-denial-of-service attack from a group called CyberTeam, which took responsibility for the downtime in a tweet that read, “Skype down by CyberTeam.” Panda Security backed the DDoS claim, though it noted that users should not be concerned about security. “Even though the consequences have been annoying for many users, their privacy and details of bank accounts used to pay for Skype services have not necessarily been compromised,” Hervé Lambert, retail global operations manager at Panda Security, said in a blog post.

Skype down by CyberTeam

Hello World !!!#SkypeDown – #SkypeOff – #CyberTeam

— CyberTeam (@_CyberTeam_) June 19, 2017

Others disagreed with the DDoS claim. Ryan Olson, threat intelligence director of the Palo Alto Networks Unit 42 threat research team, told TechCrunch that there is no firm evidence at present that this is the result of any particular attack.

Whatever the reason for the downtime, users were not happy, taking to Twitter to complain about their lack of access,  though as one user noted, the advertising in the free service wasn’t affected.

Skype is down but on the plus side, the ads in the app are working fine… #skypedown

— Darren Bootland (@darrenbootland) June 20, 2017

Skype would appear to be fully functional once again. The Skype team wrote that as of 8 p.m. GMT, it had “made some configuration corrections and mitigated the impact.” Skype said it was continuing to monitor the situation and and “will post an update when the issue is fully resolved.”

Image: philwolff/Flickr