Tony,

I'm not familiar with the ISD4004, but I've connected two different RC Systems speech boards to mobile phones. Both times I used a 1:1 audio transformer, as some of the amplifier chips don't like to have one side grounded. I got the transformers at Radio Shack.

It's also possible that the pinout you got off the internet is incorrect, but I can't help you there, I don't have any Nokia data.

Jerry.