are also suitable for voice over IP applications. The data rate is 13 kbps for the GSM Full Rate (FR) codec and 12.2 kbps for the GSM Enhanced Full Rate (EFR) codec. G.723.1 Algebraic CELP. 6.3 and 5.3 kbit/s. 30 ms frames. Algorithmic delay 37.5 msec. (CELP = Code Excited Linear Prediction). G.726 ADPCM (Adaptive Differential PCM). 40, 32, 24, 16 kbit/s. G.728 Low delay CELP. 16 kbit/s. Very low algorithmic delay (0.625 ms). G.729 Conjugate structure CELP. 8 kbit/s (and 6.4 and 11.8 kbit/s). 10 ms frames. Algorithmic delay 15 ms. 5.7.2 WIRELESS APPLICATION PROTOCOL (WAP) The presentation below is very short. A detailed description can be found in the book GPRS and 3G Applications and in Ericsson Review Nr 1 2000. Purpose To bring Internet content and advanced services to digital cellular phone and other wireless terminals. To create a global wireless protocol specification that will work across different wireless network technologies. To enable the creation of content and applications that scale across a very wide range of bearer networks and device types. Features Global standard. Optimized for narrow band bearers. Optimized for hand-held devices with limited capabilities. Integrates telephony services with micro-browsing. The WAP browser should do for mobile Internet what Netscape did for the Internet. The main advantages of the WAP standard are: Faster communication (compressed and encoded data). The wireless session protocol (WSP) increases the efficiency of transmission over wireless. Comparing with HTTP, Understanding Changing Telecommunications - Building a Successful Telecom Business Web server (WML) INTERNET Web server (HTML) www domain WAP gateway Proxy/ Mobile domain filter Binary WML Figure 5.13 An example of WAP-enabled GPRS access to Internet content is sent as binary ones and zeroes instead of plain text. The headers are encoded into short, binary sequences. These measures increase the efficiency of WAP signifi- cantly. As an example, an HTTP header of 32 bytes in plain text can correspond to 2 by