I Installed iCamsource on my mac laptop with an iSight camera.
An old G4 with airport extreme is connected to my cable modem and providing the connection the the internet.
iCam could be viewed fine on my iphone by local wi-fi, but not on 3G/Edge
After several hours playing around this was my fix:
1. Enable port forwarding on iCamsource using info here
http://skjm.com/forum/index.php?topic=402.02. In iCamsource prefs, I selected port range 12000 > 12000 i.e. 12000 in both boxes
3. On airport extreme configuration on the G4, under port mapping tab, I added new rule public & private port 12000 with local IP 10.0.1.3 (the IP of my laptop, your local IP may well differ) - (open a terminal window and type ifconfig to get your machines IP)
4. Then, under system preferences internet & network > sharing on my laptop, I had to create a firewall rule for icam, using UDP port 12000. The G4 did not have a firewall running, but I'm guessing that I would just need to repeat this step on that machine also.
What confused me, was :
that airport extreme does not allow for a port range, as suggested in the instructions so I chose 12000
iCamsource then did not seem to work with a range so I had to put 12000 in both boxes (I guess with a range 0f 12000 > 12100 there's a one in 100 chance it will use the correct port?)
I forgot that my laptop, hosting the icamsource, also had its own firewall running, and I had to add a rule for port 12000 there.
I apologize if this info has been posted before, but I could not find it - hopefully it well help someone,
Cheers
