INTERNATIONAL  TELECOMMUNICATION  UNION

		     ITU-T RECOMMENDATION SUMMARY


Rec. No. : Q.81.8

Title :	Stage 2 description for number identification supplementary 
	services

Study Group : XI - Switching and Signalling

Version : New

Date of adoption : 1992

Notes :	


			SUB-ADDRESSING (SUB)

Recommendation Q.81.8 defines the stage 2 description of the 
Sub-addressing (SUB) supplementary service for the integrated services 
digital network (ISDN) as provided by public telecommunications 
operators. Stage 2 description identifies the functional capabilities 
and the information flows needed to support the stage 1 service 
description. The stage 2 description also identifies user operations 
not directly associated with a call (see Recommendation I.130).

Recommendation Q.81.8 is specified according to the methodology 
specified in Recommendation Q.65.

Recommendation Q.81.8 does not formally describe the relationship 
between this supplementary service and the basic call but, where 
possible, this information is included for guidance.

In addition, Recommendation Q.81.8 does specify the requirements where 
the service is provided to the user via a private ISDN. This 
Recommendation does not specify the requirements for the allocation of 
defined functional entities within a private ISDN; it does, however, 
define which functional entities may be allocated to a private ISDN.

Recommendation Q.81.8 does not specify the additional requirements 
where the service is provided to the user via a telecommunications 
network that is not an ISDN.

The Sub-addressing (SUB) supplementary service allows the called 
(served) user to expand his addressing capacity beyond the one given 
by the public or private ISDN number.

The SUB supplementary service is applicable to all telecommunication 
services.

Recommendation Q.81.8 is applicable to the stage 3 description 
Recommendation for the ISDN Sub-addressing supplementary service. The 
term "stage 3" is also defined in Recommendation I.130.



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