well when comparing voip / p2p and so forth to land lines, you will see a sound difference, when using internet to place a call to a land line, youll notice the sound isnt quit as clear as a land line and some times youll hear alittle ecco, but some devices will help eliminate this issue, how ever this technology has goten better in the last few years, id say choose your server wisly because quality does differ with servers, id say if you want to hear what skype has to offer just buy a few bucks worth or what ever your currency is with skype out and test it out, atleast that way you wont be tied down in any contracts, and if you find out that its not all that you thought it was, then youd only be out a small amount of money, any thing else youd kinda need a contract, like example vonage, if your in the us, plus at&t well im not sure whats offered in your country so i cant really speak for it,, but i can say if your really wanting to save money, you may wanna consider a dedicated server like Asterisk or TrixBox but those are just ideals but very nice to setup if you have an old pc laying around doing nothing,