Question 5/II - Evolution of numbering and numbering plan
interworking for the ISDN era
(Continuation of Question 17/II, amended and expanded from 1985-
1988 study period)

It is suggested that the following (preliminary) considerations be
included in a new Question for the next study period:

Considering that

(a) numbering solutions to various ISDN-PSTN and ISDN-PDN
interworking issues (e.g., modem pooling, terminal identification,
supplementary services, service discrimination etc.) will be required;

(b) long-term network identification needs to be urgently studied;

(c) development of the NCD concept needs to be studied (NDC: National
Destination Codes);

(d) further guidance on the transition from the E.163 to E.164 numbering
plans may be needed;

(e) new application of SS7 SCCP will emerge, which may have an
impact on the numbering plans;

(f) selection procedures based on sound operational principles are
urgently required;

(g) special needs for numbering plan studies are emerging in mobile
networks,

What revisions or enhancements to the existing number and numbering
plan interworking Recommendations should be made, and what new
Recommendations should be developed?

Note 1 - A joint and unified Recommendation on numbering plan
interworking based on E.166 and X.122 should be sought in the next
study period.

Note 2 - Establishment of MMI procedures used with ISDN terminals, in
conjunction with Q.31/I of Study Group I is a matter for urgent study.

Note 3 - Study of numbering plan and numbering plan interworking
requirements for mobile networks is also an area for urgent study in
the next study period.