Installing: https://help.ubuntu.com/community/Skype
If on 64-bit architecture enable MultiArch:
$ sudo dpkg --add-architecture i386
then (for all systems)
$ sudo add-apt-repository "deb http://archive.canonical.com/ $(lsb_release -sc) partner" $ sudo apt-get update && sudo apt-get install skype
$ /usr/local/bin/skype --callto:echo123 &
--callto: <Skype user / telephone number>
Places call to the specified user or number
--disable-api
Disables Skype's Application Programming Interface (API)
--use-session-bus
Uses session bus rather than default bus