i managed to create a few users and through Jitsi to talk to each other.
once i reboot the machine, then the problems start and Kamailio cannot start.
here are a few details from my system.
-/etc/apt/sources.list the part for Kamailio
#Kamailio
deb
http://deb.kamailio.org/kamailio51 jessie main
deb-src
http://deb.kamailio.org/kamailio51 jessie main
-Version info
Distributor ID: Debian
Description: Debian GNU/Linux 8.10 (jessie)
Release: 8.10
Codename: jessie
-root@debian:~# systemctl start kamailio
Job for kamailio.service failed. See 'systemctl status kamailio.service' and 'journalctl -xn' for details.
root@debian:~# /etc/init.d/kamailio start
[....] Starting kamailio (via systemctl): kamailio.serviceJob for kamailio.service failed. See 'systemctl status kamailio.service' and 'journalctl -xn' for details.
failed!