AT&T cables with ST-BNC connectrs does it work ?

i could be wrong, but the ST connector uses a fiber optic cable inside while a BNC cable uses a copper/silver wire inside. the fiber optic cable sends data as modulations in light while the BNC bales sends data as voltage down the wire. i can't imagine how one could change light modulations to voltage midstream inside the cable, but that may be while i'm a social worker and not an engineer.

well such cables ST-BNC exist (Brand Siecom) in the tele communications industry, therefore I just wonder whether it will work out with audio CD transports and DAC or not ?

What you're probably thinking of is a BNC-to-multimode AT&T ST fiber optic media converter. It's an external powered device with an integrated transceiver that, depending on implementation, may or may not be compatible end-to-end with the FO transceiver inside your component.

FWIW, I've generally found that both ST and toslink fiber interfaces in transports and DACs sound inferior to PDIF or BNC with a good cable.

thx yes correct Dgarretson, so probably it will not work out in audio ?