Question 13/VII - Interworking between public data networks (circuit
switched and packet switched) and ISDNs, and between ISDNs, for the
provision of data services (amalgamation of Questions 13/VII and 14/VII
studied in 1985-1988)

Considering

(a) that the provision of data services may require several networks to
interwork;

(b) the framework of X-Series Recommendations related to interworking
given in Recommendation X.300;

(c) that administrations are currently operating Circuit Switched and
Packet Switched Public Data Networks (CSPDNs and PSPDNs);

(d) that administrations are planning operation of Integrated Services
Digital Networks (ISDNs);

(e) that CSPDNs, PSPDNs and ISDNs will coexist and each provide data
transmission services;

(f) that interworking between DTEs connected to each of these networks
is considered essential for the provision of data transmission services;

(g) that Recommendation X.300 defines general principles for
interworking between public networks, and between public networks and
other networks for the provision of data transmission services;

(h) that Recommendation X.320 defines general arrangements for
interworking between ISDNs for the provision of data transmission
services;

(i) that Recommendation X.321 defines general arrangements for
interworking between CSPDN and ISDN for the provision of data
transmission services;

(j) that Recommendation X.325 defines general arrangements for
interworking between PSPDN and ISDN for the provision of data
transmission services;

(k) that Recommendation X.81 defines interworking between an ISDN
circuit-switched and a CSPDN;

(l) that Recommendation X.30 defines support of X.21 and X.21bis based
DTEs on an ISDN;

(m) that Recommendation X.31 defines the method of supporting X.25 based
DTEs on an ISDN,

1. What additional Recommendations, if any, are necessary to enhance
interworking between public data networks CSPDN, PSPDN and ISDN or
between ISDNs for the provision of data transmission services?

2. What additions or modifications to existing Recommendations are
necessary?

Note - It is necessary to work these interworking issues in close
cooperation with other groups, particularly the ISDN related groups in
Study Groups XI, XVII and XVIII.