OK here is an update.. my mind is boggled!
If I am sitting on the 3300 side and dial an extension on the 5000 side I get static.
If I am on the 5000 side, the extensions arent setup, so If I dial the 3300 SIP trunk number and then dial the extension the call goes through perfectly.
Now... to complicate (or maybe simplify) it further.
If I setup a speed call from one of our DID's on the 3300 to ring through to the 5000 its rings through with caller ID on the 5000. When the 5000 answers it, I can hear the person on the 5000 side but they hear nothing.
On the 5000 side if I make a call across the SIP trunk by dialing the SIp trunk number (just like my intercom call above) again I can here the person on the 5000 side however they cannot hear me.
Any thoughts? Strange thing is I have a site with the exact same setup that works perfectly.