Wow, it's amazing it's working.
For anyone who is interested in it, here's my complete work around:
Configure the FritzBox for DynDNS:
http://www.avm.de/de/News/artikel/newsletter/dynamic_dns.html Make VPN:
http://www.avm.de/de/Service/Service-Portale/Service-Portal/VPN_Praxis_und_Tipps... Install: FRITZ!Box-Fernzugang einrichten
Install: FRITZ!Fernzugang
Check if your VPN tunnel is working:
192.168.178.1
Übersicht > Verbindungen > VPN hergestellt,
Change in FritzBox "reg_from_outside=no" to yes
http://www.antary.de/2011/08/02/fritzbox-voip-von-ueberall-aus-nutzen/
How to edit configuration files:
To turn on the Telnet Server in the Fritzbox:
pick up your phone and dial: #96*7*
Start the Windows Telnet Client > Putty
Password is same as in the FritzBox
Start the Fritz!Box editor nvi.
To edit the voip.cfg file:
Type: nvi /var/flash/voip.cfg
Type: / search text
To enter edit mode type: i
Make the needed changes
Return to command mode: ESC
Safe the file: :w
Exit nvi editor: :q
Reboot Fritz.Box: reboot
Make a profile in PhonerLite with following settings:
Proxy/Registar: 192.168.178.1
STUN server: stun.sipgate.net
Domain/Realm: fritz.box
Register: yes
MWI: yes
seconds: 900
User name: 622
Displayed name: my name
Password: ****
Authentication name: empty
Local port: 5060
UDP: yes
Multicast DNS: yes
UPnP NAT: yes
That's all.
For me it is working in this configuration, I can now connect to the Fritz.Box worldwide and make/receive all the calls via my FB.
PhonerLite is the best, thanks.