Recommendation U.25
REQUIREMENTS FOR TELEX AND GENTEX OPERATION
TO BE MET BY CODE– AND SPEED–DEPENDENT TDM SYSTEMS
CONFORMING TO RECOMMENDATION R.101
(Geneva, 1980)
	The CCITT,
considering
	(a)	that it may be desirable to use code– and speed–dependent TDM systems described in Recommendation R.101 in the teleprinter switching networks;
	(b)	that it is essential to transmit the full range of telex signals for types A, B, C and D signalling;
unanimously declares
	that the following requirements for telex and gentex operation should be met by code– and speed–dependent time division multiplex systems conforming to Recommendation R.101.
1	Transmission of type A (control) signals shall be accomplished within the tolerances specified in Table 1/U.25.
2	Transmission of type B (control) signals shall be accomplished within the tolerances specified in Table 2/U.25.
3	Transmission of type C signals shall be accomplished in accordance with Table 3/U.25.
4	Transmission of type D signals shall be accomplished in accordance with Recommendation U.12.
5	Each of the following modes of bothway telex signalling shall be capable of being accomplished on a single circuit:
a)	type A in one direction and type B keyboard in the other;
b)	type A in one direction and type B dial in the other;
c)	type B keyboard in one direction and type B dial in the other;
d)	type A in both directions;
e)	type B dial in both directions;
f)	type B keyboard in both directions;
g)	type C to Table 1/U.11;
h)	type C to Table 2/U.11;
i)	type C to Table 3/U.11.
6	A single terminal shall be capable of handling any of the signalling combinations shown in § 5 above and at least five of them simultaneously.
7	The nominal pulse duration (other than dial pulses) shown in Tables 1/U.25, 2/U.25 and 3/U.25 for Signal transmitted to telex have a ± 3 ms tolerance except where otherwise indicated.

TABLE 1/U.25

Montage:  Reprendre les originaux du Livre Rouge (sans corr.)
TABLE 2/U.24

Montage:  Reprendre les originaux du Livre Rouge (sans corr.)
TABLE 3/U.25

Montage:  Reprendre les originaux du Livre Rouge (sans corr.)