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15

Mobile phone networks have shown even higher growth rates than the Inter-
net, according to many reports from analysts. We explain this by a confluence
of several factors, such as a satisfactory service for telephony (though not
exactly a 100 percent replacement for QoS and Centrex features of wireline
telephony), a real need for wireless services, and, most of all, mobile telephony
has no equivalent in existing wireline telephony networks. Circuit-switched
mobile telephone networks have surpassed wireline telephony, especially in
new emergent economies where the wireline infrastructure is less developed.
All emerging mobile communications are IP-based.

NOTEMobile telephony has proven in the market that users will gladly trade

in less than perfect QoS for the convenience of mobility. We will use this as

reminder when discussing QoS in Chapter 18.

Marketers and business planners did not take long to discover that the inter-
section of mobility and the Internet could be an even better combination of two
already excellent ingredients. Several approaches are pursued to make this
happen:

■■ Add Internet-style services to present circuit-switched mobile networks, such

as the Short Messaging Service (SMS) and web access—An attempt at what

was marketed as web access was the Wireless Access Protocol (WAP),

SIP Application Level Mobility

CHAPTER