Last month, Skype service was down for several hours for some users. Microsoft later explained the cause for the outage and apologized to its users.
We released a larger-than-usual configuration change, which some versions of Skype were unable to process correctly therefore disconnecting users from the network. When these users tried to reconnect, heavy traffic was created and some of you were unable to use Skype’s free services, including messaging, presence, and contact list management. Others could not sign in or out of Skype altogether, or make calls to landlines or mobile phones. Skype for Business was not impacted.
Now, they are offering 20 minutes of free calls to over 60 landline and 8 mobile destinations around the world. This free calls will be available to use for 7 days.