POTS uses modems to connect to each computer with the maximum bit rate of 56 Kbps. It’s a low band width network. It can only use H.723.1 as its audio codec method and H.263 as its vidoe codec method. Because of the bandwidth, its hard to transmit high quality videos over POTS. But for voice, it is a suitable selection.

ISDN has two basic types of service: BRI with a total of 144 Kbps and PRI with a total of 1536 Kbps. It supports high quality stereo sound (G.728). But for the video codec, it uses H.261 codec method that support CIF format with the resolution of 352 * 288 pixels and QCIF format with the resolution of 176 * 144 pixels. It can be targeted for teleconferencing applications where motion is naturally more limited. Class 1 will only support QCIF with 7.5 fps and cannot realise full animation whereas class 3 supports CIF with up to 30 fps but needs rich bandwidth.

LANs consist of 10 Mbps Ethernet, 100 Mbps fast Ethernet, 1000 Mbps gigabit Ethernet, 100 Mbps FDDI, 25 or 50 Mbps ATM or 4, 16 or 32 Mbps Token Ring segments. It is the ideal choice to support multimedia transmission approaching television quality. However, except for the use of optical cables in FDDI, and fast Ethernet, the geographical area of the LANs is restricted due to the signal decay and interference.

Table 2-10 lists the comparison of different networks ad their related audio, video and data standards.

Table 2-10 Comparison of different networks ^[61]