The two main factors determining the voice quality of your calls will be the
quality of your broadband connection and the quality of the phone you
If you are using recommended VOIP hardware for your calls you should expect quality at least as good as a mobile call, in most cases there should be no noticable difference between a VOIP call and a normal landline call.
voice quality of a soft-phone is typically alot less than you would
expect on a VOIP hardware solutions unless you are using a modern
multimedia PC, a quality headset and non-free software.