boiler room

/B OY1 L ER0 R UW0 M/
noun
  1. 1

    A room in a building that houses the boiler(s) and similar equipment.

  2. 2

    A compartment on a steamship that houses the boiler.

  3. 3

    A telemarketing firm that makes cold calls.

Source: https://en.wiktionary.org/wiki/boiler%20room