Transmission distance of the DSGW-030 gateway

How far is the transmission distance of the gateway?
Does a room have to have a gateway?
Can signals go through walls?

In open environments, the Zigbee function of the gateway has the potential to support transmissions over distances of up to 100 meters. The extent of coverage in the actual installation ought to be evaluated with reference to the manner in which the gateway is set up, the environment in which it is situated, and the fabric of the shelter.