Rcaman -

Thanks! I'd call it hummmmmm. It definately sounds like AC is present, it's "talk-overable", but annoying.

I don't have a scope frown

One thing - the voltage (-24vdc) is present on AB/AG with no line cards (K400E) installed. However I have 5 line cards, have tried each one anyway, to no effect.

I'm positive the intercom card must have the additional filtering you describe, becasue as I said, it's clean and clear across it's tip and ring.

I guess what I'm trying to figure out is if ITT never intended AB/AG to be used (directly) for voice - and that if you wanted to do that, then you would have to buy thier intercom card.

One thing I never mentioned - the hum is only present on AB/AG - not the CO lines.

Thanks
Matt