There is an interesting read on the subject here [Link: techhealthperspectives.com] , they are using Skype as an example, however keep in mind that that any new hardware based VC unit - either "high end" i.e Cisco or Polycom, "mid-grade" i.e Lifesize or entry level i.e Grandstream is capable of a very robust encryption and should prompt you if the call is secure.