It was developed by the military for secure communications. That depends on many things.
Indoor propagation is affected by the type of construction of the walls and floors.
It depends on where in the building the radios are mounted. A line of sight path has less loss and therefore greater range than a path through walls. Metallic structure attenuates signals much more than wood, cement or plaster. If the wave must be propagated around corners by diffraction, the range can be severely restricted. Typical spread spectrum systems have an indoor range of up to 2,000 feet unobstructed, and up to 400 feet through standard walls.