Continuity test on fiber optic cable

I've recently found out that in our rented office space we have a fiber that terminates in the office next door.

I want to test to see if it's intact. So i tried shining light from a bright flashlight, but none comes out the other end.

Is this because the fiber is broken somewhere, or is it because only IR light will propagate through the fiber?

Any help would be greatly appreciated.