Microsoft's Skype voice and messaging app experienced a major service disruption Monday morning that crippled the app's core features for some users. The company has acknowledged that it's currently working to resolve "an issue that is affecting Skype in a number of ways" — but the problems have now stretched on for several hours. They're also being felt worldwide, so the issue isn't limited to any particular geographic area.

The glitch is showing all contacts as offline, even for users who are actually logged in, making it impossible to place voice calls. Microsoft says the messaging side of Skype is still mostly working properly, though the company notes "a small number of messages to group chats are not being delivered."

We are aware of an issue affecting Skype status at the moment, and are working on a quick fix: http://t.co/ymSzmrgEX0 pic.twitter.com/8LoqqL0hh7 — Skype Support (@SkypeSupport) September 21, 2015

If you're not currently signed into Skype, you might have a tough time getting online while the problems persist. Users can also expect delays before changes to their Skype account (profile, calling balance, etc.) are reflected across the service. "We're doing everything we can to fix this issue and hope to have another update for you soon."