20-31 VoIP eng

Today, the accumulated volume of data traffic is on the verge of surpassing the accumulated volume of voice traffic in all public networks. Given the growth in the areas of wireless voice and data, we see that the combination of mobile and Internet communication constitutes the driving force behind third-generation wireless systems, which promise to support at least 144 kbit/s (384 kbit/s) in all radio environments, and up to 2 Mbit/s in low-mobility and indoor environments. The standardization of third-generation wireless systems is rapidly progressing in all major regions of the world. These systems— which go under the names of IMT-2000 (ITU), UMTS, and EDGE (ETSI/3GPP)— will extend the services provided by current second-generation systems (GSM, PDC, IS136, and IS-95) with high data-rate capabilities. The main application for these services will be wireless packet transfer; for instance, for wireless access to the Internet. However, support will also be provided for high data-rate circuit-switched services, such as real-time video.