Assuming you have some kind of headset or at least a cheap mike with speakers in the worst case, I bet you’ve already tried using some voice-over-IP services and you may have liked it except its being rather inflexible, heavy and maybe even complicated to set up.
Secure User to User Communication
CSpace is a freeware that offers its users the possibility to securely communicate over the internet using public RSA keys with a strength of 2048 bit. Every user creates a 2048 bit RSA key for himself and maintains a contact list of names associated to public keys of other users. Public keys are exchanged using a key server. Cspace users can chat with each other, transfer files and even use a remote desktop feature.

