4
Voice over Wireless
Despite the growing number of Web 2.0 and mobile Web 2.0 applications being used in B3G networks (cf. Chapter 6), voice telephony continues to be the most important application in a mobile network. As mobile operators have a long history of making voice telephony work over wireless networks, and as they control the mobile infrastructure, they are in a good position to secure a sizable market share of tomorrow‘s wireless telephony business. Up to 3G UMTS, voice telephony was tightly integrated into the wireless network infrastructure. As a consequence mobile operators enjoyed a voice telephony monopoly in their networks. From the user‘s point of view the situation changed slightly in many countries in recent years due to fierce competition. MVNOs sprang up who bought buckets of voice minutes from mobile network operators for reselling to customers under their own brand. From a technical point of view, however, the network operator remained in charge, as MVNOs were mere resellers of voice minutes.
In B3G networks the situation has changed. As already discussed in Chapters 2 and 3, B3G networks no longer have a separate core network for voice telephony and voiceoptimized protocol stacks in the radio network. As in fixed-line broadband networks, all services and applications are now delivered via the Internet Protocol and a packetswitched connection. This brings both opportunities and challenges. On the positive side, from an innovation point of view, network ...
