asterisk users - Dec 2004 - Asterisk to sip client behind Firewall/NAT - can call but cannot receive calls ?

Hi,

I have following setup:

BT100 ---- Firewall/nat 1 (www.ipcop.org) ---- Internet ----Firewall/nat2
(Vigor) ---- Asterisk .

I'd like to use BT100 as local extension to Asterisk. I've done simple
setup
and BT100 can call Asterisk and place outgoing calls. However I cannot set
him to qualify, cause it is claimed as unreachable.

I have port redirection at Firewall 1 (to 5060 and rtp 5004 to grandstream)
and 5060 and rtp ports on Firewall2. But I guess I am missing something.
I've setup Asterisk to work behing nat and it works OK, on same route and
same local network Iax phone is operating also ok in both ways.

On grandstream I've setup public NAT adress, then keep alive to 10 sec,
(tried also some other setups but didn't work).

I'm so close to working state, so would kindly ask for any guidance (to save
my hair) :-)

Also I'm missing some understanding of SIP in this story: on what ports on
Asterisk machine does Grandstream connect RTP ?  Do I have to transfer some
other ports on Firewall2 because of Grandstream RTP connection ? If
everything works on outgoing calls there must be some little condition that
gets changed when I try to reach grandstream - what could that be ?

If anyone has working scenarion, please be so kind to help.


Regards,

Rob.