General description of an international TDM system

Figure 1/M.850 illustrates a basic international TDM telegraph system. The system operates via an international TDM telegraph link operated at 2400 bit/s and has a capacity of 46 telegraph channels at 50 bauds. Other modulation rates up to 300 bauds can be accommodated (with resulting reduction in channel capacity) as shown in Recommendation R.101, Table 1/R.101 [1].

The international TDM telegraph system may be carried over a dedicated voice-frequency link as shown in Figure 1/M.850 or multiplexed with other TDM systems or other services onto a higher bit rate data transmission system on a voice-frequency or digital data transmission link as shown in Figure 2/M.850.

International telegraph systems may also be carried on high level (e.g. 50, 56 kbit/s) data transmission links utilizing analogue group band or on digital (64 kbit/s) paths. Examples of such multiplexing arrangements are illustrated in Recommendation M.1300.