There is always some software that needs installing. Personally I cannot see the point of all this, I use Messenger 6.2 for yacking to the colonies....the advantages are;
1) it is easily available and usually comes installed on most computers.
2) It is free.
3)The sound is crystal clear and one can have a video of one's ugly mug at the same time.
4)The 'alerts' work very well.
5) It does not seem to cause many conflicts.
Until any intenet phone service can beat this they are onto a loser.