I'm not sure which of the cartridges suported external bells & horns. There were 2 Feature Packs cartridges, a MOH/Page cartridge and a Power Fail cartridge.
6102 was the MOH/paging card. I have one here; from what I've read, it isn't the answer. 6103 was the power fail/external signaling card. It looks like a more likely candidate, but I don't have one, and don't want to order one without knowing more about it.
What would be especially interesting is if the 6103 card was anything like I've heard the 6102 was - essentially just a plastic box with some jacks and connections to the main board, without anything fancy in between. If anyone knows more about them, maybe I won't need any additional hardware at all!
--Keith
