Skype-to-Skype calls to other users are free of charge, while calls to landline telephones and mobile phones (over traditional telephone networks) are charged via a debit-based user account system called Skype Credit.
The latest version of the communication software combines features of Lync and the consumer Skype software.
Users may have more than one account; it is not possible to count users, only accounts.
The volume of international traffic routed via Skype is significant. Later, a mobile version was created for Windows Phones.
When the company introduced Office 2013 on 27 February 2013, it was announced that 60 Skype world minutes per month would be included in Office 365 consumer plans (Home and Personal, and University).
Furthermore, Microsoft discontinued two of its own products in favor of Skype: In a month-long transition period from 8 to 30 April 2013, Microsoft phased out its long-standing Windows Live Messenger instant messaging service in favor of Skype, although Messenger continued in mainland China.