14.3 Enhanced Voice Service

Voice services have been the bread and butter of wireless operators for a long time. Voice as the killer application is expected to continue for quite some time into the future as well. However, there is evolution in terms of enhancements to the traditional voice call. One aspect is that the current circuit switched voice call may be carried over packet networks in the future. Hence the capability to support voice over IP is slowly being developed in 3G networks. One of the key requirements of enabling VoIP is, of course, QoS support. With support for QoS being built into 3G networks, VoIP can be delivered in the near future. VoIP is already utilized in core networks and in enterprises over LANs. However it is not yet a part of the mainstream voice communication technology. End users really do not care about the technology being used to deliver the voice service: what matters to them is the voice quality. With the new codecs such as AMR in 3G networks, voice quality is expected to improve over wireless networks.

In addition to supporting VoIP, the signaling mechanisms used to establish the voice calls are also evolving. The Session Initiation Protocol (SIP), which is developed in the IETF, has a lot of momentum and is included in the standards of 3G networks (both 3GPP and 3GPP2). SIP-based call control for supporting VoIP is expected to be widely available in the next few years . With SIP it is also possible to add new features to the traditional voice calls and create a rich call experience for the end user .

Rich calls can be defined as calls or sessions in which voice or video conversations are supported with concurrent access to data services, such as transferring an image or file or any other value add to the call itself. An example of this is a conversation between two parties that requires both users to take a look at some information on the Web to make a decision or if one user would like to send the other user an image of the location that he is currently at or a music clip from the concert that he is currently attending .