Question 16/XI - Interworking of signalling systems
(Continuation of Question 13/XI studied in 1985-1988)

Considering

(a) that Recommendations on interworking, using the SDL language, of
most combinations of the CCITT Signalling Systems have been prepared
(Recommendations Q.601 to 685 in Volume VI-6 of the Blue Book);

(b) that as a result of the experience gained during the elaboration of
the logic procedures contained in those interworking Recommendations,
some rules have been prepared which should be complied with when
specifying new signalling systems and which will help to facilitate
interworking between existing CCITT Signalling Systems and new
signalling systems (see Recommendation Q.607);

(c) that new switching and transmission systems may give rise to new
interworking problems;

(d) that further updating of signalling system specifications may be
necessary;

(e) that the interworking of signalling systems may be affected by
changes in other procedures, such as call-routing and echo control;

(f) that the continued enhancement of existing, and generation of new,
user parts for Signalling System No. 7 will require changes to
interworking;

(g) that the ISDN and new mobile services may give rise to new
interworking requirements;

(h) that ISUPDSSI interworking Recommendation is using arrow diagrams
with primitives for interworking, accordingly the Interworking logic
block might have to be modified to work with primitives facing ISUP, and
FITES
and BITES facing existing Signalling Systems (Nos. 5, 6, R1, R2, and
TUP);

(i) that a complete set of interworking diagrams for ISUP interworking
with existing signalling systems using FITES and BITES was developed
during 1985-1988 study period and is annexed to this Question,

What new interworking Recommendations and what extensions to existing
interworking Recommendations should be specified?

ANNEX

(to Question 16/XI)

Signalling System No. 7 ISUP interworking diagrams

(See Contribution COM XI-4)