Is this old doorbell 12V or 220V?
It's low-voltage. The wires you can see would never be rated for mains voltage. I doubt that anyone, anywhere has ever made a doorbell that runs directly on mains voltage. It would be far too dangerous.

The bell itself doesn't care about AC vs DC, so probably AC for simplicity.

As far as replacement, either get another one just like it, or build a small circuit that rectifies/filters the AC and apply the resulting DC to any electronic beeper or sound generator you like.