Skype differs from other VoIP-systems by several factors:
Skype is very popular. During the first week in August of 2003, more than 60 thousand people downloaded the Skype-client. Today, Skype is available for the following operating systems: MS Windows, MacOS, IoS, PocketPC, Android and Linux.
MCK communication is a part of Citel technologies, The VoIP Migration Company. MCK products like EXTenders, Gateways, and DTI call center solutions, are now available through Citel.