Asterisk and nat + virtual machine

Hi all,

my PC is located behind a router. Inside, I installed AsteriskNOW in a virtual PC (VMWare).

I frowarded all router ports to the virtual machine IP. My modem is registered to a dynamic DNS with the address

In the sip.conf file, I configured the following parameters:

I can do the following operations:
-connect sip extensions located inside the local net with the proxy as the local ip address of the virtual machine.
-make calls between these extensions.
-connect Asterisk to sip trunks (outside local net) and make calls through these trunks from local extensions.
-connect to the virtual machine through: ssh
-connect to the Asterisk web server or by putting the local ip of the virtual machine.

I can not do the following:
-connect sip extensions by declaring the proxy “” (either from inside local net or from outside local net)

Can anyone help me to do solve this problem?

N.B. The fact that I can connect through ssh and http to proves that port forwarding works well.