Summary

• Mobile networks require a complex infrastructure, mirroring that of the telephone network and the Internet.

• Voice networks are formed from MSCs (Mobile Switching Centers), the equivalent of telephone exchanges. GPRS networks are formed from SGSNs (Serving GPRS Support Nodes), equivalent to Internet routers.

• A WAP Gateway allows users to dial up a network from their mobile phones. A WAP server is equivalent to a Web server.

• Open WAP networks allow access to any site. Closed WAP networks allow access only to those of the operator and its partners.

• Internet phones require IP addresses, which are in very short supply.