Saved By The Bell!

This idiom is pretty funny and logical, despite of others!

It comes from the boxing, when a boxed was saved from being counted out by the bell that ends a round.

So, you use that basically in the same situation. For example, you're about to tell something really important to someone, but the cellphone rings. Or, when you're late to take the schoolbus and the driver's phone rings. So in this case he'd have to stop to take it, and you'd have a couple of more minutes.

These are the kind of situation when you can use it.

Questions?!