Ah. Helpful info. Yeah... I've just forwarded those ports, as you assumed. I'll remove those settings.
Also, I disabled sip alg, as you recommended.
It is odd though... when you are having problems and cannot install, it connects you to a link that tells you the following, so I thought that might fix it:
What ports should I keep open on my router/firewall?
In order for your OBi to be able to send packets w/o interruption, please configure your router as follows:
Allow Outgoing:
TCP Ports: 6800, 5222, 5223
UDP Ports: 5060, 5061, 10000 to 11000, 16600 to 16998, 19305
Allow Incoming on UDP Port: 10000