You are actually asking about a couple of different things.  First, your 'Wireless Modem' (actually a wireless router/modem) is only involved with the Internet (also referred to as WWW) and the assigning of IP Addresses for devices inside of LAN for the purposes of becoming a portion of the world wide Internet.  This is what allows you to connect to sites like Google, Amazon, and CNN.  Things that are on the outside of you router/modem are said to be on the WAN (Wide Area Network) and things ins