Internet rules!
It is now even encroaching on the world of English language teaching. English classes on skype will never be the same as a face to face English class with an English teacher who you can see off screen aswell as on screen.
The big difference has to be the convenience that telephone classes offer both the student and the teacher - class timetables, cancelled classes, etc.
imagine the above is obvious however we wish to mention another factor that can be good for the travelling English teacher and the English student in need of saving some money and so has chosen skype or telephone English classes. The meeting of souls or needs of an English teacher travelling abroad (not teaching English in an academy but rather teaching over the phone whenever possible) and an English student with a busy social life, is ideal.