Plenty of competitors have emerged but they all have gotten strong-arm tactics from Skype, whether we're talking about the Nimbuzz fiasco or Skype blocking fring, or Skype buying Qik, no competitor has been able to make it easy for customers to make a switch. Qik came the closest (unlikely the others, they didn't need Skype integration due to their deal with Sprint) so Skype just bought them.