The wireless CSI

Wireless telecommunications have  been around for more  than eight decades. First we had  the  radio in the  1920s. During World War II, we had the  inception of walkie-talkies. These  led to the development of cell division multiple access (CDMA), one of the  most popular carrier services supporting cell phone net- working  today. In the  1960s, the  first wireless transports connected mobile telephones using  radio telemetry, which connected the  caller (using radio fre- quency channels) to the circuit-switched PSTN.
 

Wireless  telephones used radio telemetry until the first cellular network towers began  to evolve in the early 1990s. The wireless telephones went through many  variations, with each iteration getting smaller, cheaper, faster, and  better. Wireless telephones first used analog modulation, then digital  and  hybrid techniques — and  even  satellites.

How does VoIP fare with the  wireless CSI? The jury is still out,  but  at this point little can be done with VoIP over  cellular networks. Why? Because the  cellular network, even  though it goes  over  the  wireless CSI, is essentially an extension of the  PSTN.

However, there are two exceptions to this.  First, a computer could be running a VoIP soft phone application (see Chapter 10), which allows  the computer’s user to be connected to a VoIP network and  conduct voice conversations through the  computer connection. The computer’s connection to the  Internet or to a company’s WAN could be established through a cellular data service. (Many cellular telephone companies are now offering high-speed data con- nections for their users.) In this  case, VoIP is being  operated through a cellu- lar connection, which means it is going over  the  wireless CSI.

The second exception is for dual-use telephones, which can access both cel- lular networks (the wireless CSI) and  VoIP over  wireless computing networks. These phones are able  to place VoIP calls over  a wireless data network when  one is within range, and  over  the  regular cellular network when  one is not.

It is easy  to confuse wireless networking with the  wireless CSI. They  are not the  same. Wireless networking is an extension of Ethernet networking, and  is discussed in depth in Chapter 8. The wireless CSI is, today, the  cellular net- work used predominantly for voice communications.