Skype, Microsoft’s online telephone and video service, said it identified the glitch that prevented some users from making calls, and by late Monday GMT, the issue had been resolved.
“Skype services have been fully restored,” the company said via a blog post update at 23:53 GMT on Monday.
Skype said on Monday that some users are unable to make calls because their settings showed that they and their contacts are offline, even when they are logged in.
Some messages to group chats are not being delivered and users not already signed in may face difficulty while accessing their accounts.
The company said the issue did not affect Skype for Business users.
Skype added that users could experience delays in seeing changes made to their accounts, such as credit balance and profile details.
Some of you may experience problems with Skype presence and may not see online. We have detected an issue with the status settings of Skype. Affected users will not be able to change their status, their contacts will all show as offline and they will be unable to start Skype calls to them.
Users may also face difficulty loading web pages on the Skype Community, the company said in a blog post.
In an earlier post, Skype had said its instant messaging and Skype for Web services were not facing technical issues.