in service
Functional and able to be used by others. We need to restore power before we can put this part of the railway back in service. A: "Sorry, the elevator isn't working." B: "Aw, man. Do you know when it'll be back in service?"
in service
[of something] operating or operable. (See also something in(to) service">put something in(to) service.) Is this elevator in service?