A Skype outage downed calls around the world today. Some users reported not being able to make calls, other had calls dropped mid-conversation.

The popular low-cost phone service has been hit by major outages twice this year. Today’s outage was larger than a major two-day outage the phone service had in 2007.

 Charles S. Golvin, an analyst for Forrester Research, said “For a communications system this large to go down, it’s almost unheard of. Usually when phone lines are disrupted, the blackout is confined to a specific geographical area. This is worldwide.”

Skype attempted to contact its customers by using Twitter when its service went down. Skype posted “Some of you may have problems signing in to Skype — we’re investigating, and we’re sorry for the disruption to your conversations…Our engineers and site operations team are working non-stop to get things back to normal — thanks for your continued patience.”

Skype said it may take a few hours to get the service back up and running, but as of this evening there were still outages in some areas. Skype did say that group video calling and some other features would take longer to return to normal.