Question 13/XVII - Interchange circuits
(Continuation of Question 13/XVII, 1985-1988; revised wording)
(Of interest to Study Groups VII, XVIII)

1. Study of points arising from the implementation of Recommendations
V.10, V.11, V.24, V.25, V.25bis, V.28 and revision thereof as required.

2. Continuation of the study of the electrical characteristics of
interchange circuits with a view to:

a) defining techniques for monitoring power OFF and fault conditions in
Recommendations V.10 and V.11;

b) defining the parameters of the line signal at the physical
interchange point (practical interface) and/or the remote end of the
interconnecting cable in addition to or in place of the internal
parameters presently defined in Recommendations V.10 and V.11. This will
permit the removal of the statement "The parameters defined in this
Recommendation are not necessarily measurable at the physical
interchange point. This is for further study" which appears in both
Recommendations V.10 and V.11;

c) introducing characteristics for dynamic balance, common mode
rejection;

d) defining parameters for a new V-Series Recommendation (related to
Recommendation V.11) for electrical characteristics of balanced
multipoint interfaces.

3. Further studies for revised or new logical circuit definitions
appropriate to Recommendation V.24, together with definition of the
interaction between circuits and, in particular, the study of:

a) definition of circuits for multiple speed select as used in
appropriate modem Recommendations;

b) redefinition of circuits to accommodate V.25bis serial autocall
protocol;

c) implications arising from implementation of error control functions
in DCEs.

4. Timing considerations for several interworking arrangements.