"Bridge at '109.105.109.163:47779' isn't reachable by our firewall policy." means that you have set your "ReachableAddresses" torrc option to tell Tor that it shouldn't even try to reach that address. Thus Tor is opting not to try to reach that bridge.
Perhaps you set ReachableAddresses using Tor Browser, by answering "yes" to the "Are you only able to reach certain ports?" question in earlier versions of Tor Browser? If you tell your Tor that it should only attempt connections on ports 80 and 443, and then you configure it to use a bridge on port 47779, you'll get the above message.
Since that set of options was indeed confusing users, we changed it, as described here:
https://trac.torproject.org/projects/tor/ticket/11405#comment:7
and that change went out in Tor Browser 4.0:
https://blog.torproject.org/blog/tor-browser-40-released
As for your general question, it really depends how exactly your firewall is restrictive.
You might also enjoy the "meek" pluggable transport as an alternative that gets through restrictive firewalls in a different way than Obfsproxy does:
https://blog.torproject.org/blog/how-use-%E2%80%9Cmeek%E2%80%9D-pluggable-transport