[Asterisk-Users] Almost there--Remote connection

[Ferguson, Michael]

G'Day All;

Greetings and best wishes. I need some help as follows:

My Grandstream 100 is at a remote location on broadband and connects to
my * server else where.
>From a POST line I dial the 3 to the * server and selects the ext # of
the remote GS100 IP phone.
The GS100 rings. When answered I can clearly hear everything coming from
the phone that's calling in.
The caller cannot hear anything coming from the GS100 IP phone.

If I make a call out from the GS100 to a POTS #, the POTS number rings.
Upon answering, the GS100 can also hear everything from the POTS phone
but the POTS phone is not hearing anything from the GS100.

I believe the phone is setup right.

The * server is behind a firewall and I have opened ports 
10000-10100
5060
5004
4569

So it seems that my something is not allowing signal from the GS100 IP
phone out but is allowing signal in.

Any thoughts one where/what I should be modifying?

Thanks much.