I have EQ2voiceservice.exe as one of my explicit exceptions.
To get voice chat working last night: I had to disable my firewall completely (AVG), change channel to the one I want, confirm it works (just key-press and not getting the 'you're not in channel' was enough), re-enable my firewall, and then return to the game. This leads me to wonder if the channel joining is being done with a different, and thus far unnamed, application.
I was the only one in the house playing EQ2 last night (my boyfriend was doing computer repair work for a client and then playing SIMS3), so it had nothing to do with any conflict on the router.
Oh.. and eq2voiceservice.exe crashed this morning right after I launched the game. *shrug*