McPork

Hi everybody, sorry if this is trivial to you, but I've been searching for a while and couldn't find a definite answer. Is it possible with the Asterisk software package to use a RasPi at home with dyndns such that 1) it serves as a registration server (i.e. one does not need any extra service such as linphone.org) 2) it allows encrypted voice (and video) calls from one Asterisk-RasPi to another one located elsewhere on the internet 3) one can connect some sort of a headset or even a standard phone...