@iori
evidently you have been missing out on some keywords piyo mentioned, it is a 3G and not a 3GS.

jailbreak for 3G on 3.1.3 is possible, in fact i'm running on 3.1.3 since pwnagetool came out.

if you have a officially unlock 3gs, no harm trying.

officially unlock means phones that originates from malaysia, singapore, hong kong, new zealand and as such which provide officially unlock phones.
if it fails just restore then, no harm done.

locked phones are from US and UK namely.

@hanturaye
please refrain from posting if you don't know what you are talking about.
where did you pull 04.11.07 from?
your own custom made baseband ah?

and when you restore your baseband will upgrade to 05.12.01, unless you are using a custom firmware.

please la bro we are here to help others in the community out and not adding more to their confusion.

@kenshin
its a locked baseband, no unlock yet
and definitely you've probably upgraded your phone before to 3.1.3 and downgrading it again.

there's no unlock for you currently, except for hardware unlock which basically swaps your updated baseband chip with a old one. This process is very very expensive as well.

keyword annouced
it is still not available to public

i don't think there would be any JB for 3.1.3 on 3gs with newer bootrom as all the exploits are kept to be ready for OS4.

of course it should work la bro
its a 3g not a 3gs

and for your question previously, changing boards yes it can be done but its gonna cost you a super whole lot of $$

@peter
i think you have a 3g which does not need ECID at all

@bbs
you can't do anything.

there's alot of redundant post again and again, let me just put it straight

3G, You can jailbreak on 3.1.3 with pwnagetool
3GS with old bootrom, You can jailbreak with pwnagetool/snowbreeze as well provided that you have not updated to the new 3.1.3 firmware.

3GS with new bootrom on 3.1.3, You CANNOT do anything at all at the moment.

you cant cache your shsh on saurik's server at the moment
due to the extreme traffic currently hogging them.

just restore to 3.1.3 then run spirit

even if you've activated it, you still can't unlock

there's no unlocking tools yet for 05.12.01