I've just reconfirmed this bug exists with several Telepathy ?backends? when attempting to use a SOCKS proxy... an HTTP connect proxy is configured to forward connections through the available socks proxy.
I've switched to Pidgin and this is confirmed to work, however it's in no way a solution to any problem... at best it's a cheap work around. Here is one solution...
Place these into /etc/rc.local and run it:
daemon -n socat5223 -- socat -ly TCP-LISTEN:5223,fork,reuseaddr SOCKS4A:127.0.0.1:talk.google.com:5223,socksport=9050
daemon -n socat5222 -- socat -ly TCP-LISTEN:5222,fork,reuseaddr OPENSSL:127.0.0.1:5223,verify=0
You'll need both the daemon and socat packages installed. Then one should be able to set localhost as the server to connect to. socat can also make use of HTTP connect proxies, I believe.
Why you wouldn't put this into your application is beyond me, it's a little bit of shell scripting and it would close the bug... you could even make use of UNIX domain sockets. It's only politics that keeps this bug open, ppls own agendas getting in the way of implementing options/features users are requesting. "Why would an application developer care about the available features on an HTTP proxy they would likely never use?" The use should be able to configure and use proxies, don't know why this is so difficult a concept to understand.