Recommendation I.220 - Common dynamic description of basic

telecommunication services



1.	Introduction



	This Recommendation provides the dynamic description of basic telecommunication services. The dynamic 
description for basic telecommunication services using the circuit-mode means of service establishment/dis-
establishment is provided in section 2.  The packet-mode description is for further study.



	The dynamic description shows the flow of events, and states within the service, in a time sequenced format and 
identifies all possible actions relevant to the service as perceived by end-users.



	Although the service is described from the end-user perspective it does not concern details of the human-to-
machine interface itself. In addition, the service description considers the network as a single entity. For example, infor-
mation flows between nodes within the network are not shown.



	End-user perceptions of the service are shown in terms of "user/network" interactions. Internal network actions are 
included whenever they are or can be perceived by an end-user(s) during the operation of the service, and as required 
by SDL drawing rules.



	The terminology and the meaning of the "user/network" interactions are provided in Annex A. The means for devel-
oping dynamic descriptions, e.g. the SDL symbols and their usage, is further elaborated in RecommendationI.210.



Note - In the development of the circuit-mode dynamic description, the bearer services - speech, 3.1 kHz audio, unre-
stricted, and the teleservices - telephony, Teletex, Telefax 4, mixed-mode and Videotex were considered. Others are for 
further study.



2.	Circuit-mode dynamic description of basic bearer and teleservices





     (BASIC CALL PROCESS)  































































































































































































(BASIC CALL PROCESS

Macro definition outgoing call)

























































































Note 1 - This is an event which may occur at the S/T reference interface and can be reflected at the user interface.







(BASIC CALL PROCESS

MACRO DEFINITION INCOMING CALL)  

































































































































































































Note 2 - This is an event which may occur at the S/T reference interface but is not reflected at the user interface.























































































































































































































































































































































































































































ANNEX A



(to Recommendation I.220)



Terminology for "user/network" interactions





	SETUP		  Interaction across the "user/network" interface regarding  a service request.



	REPORT	  Interaction across the "user/network" interface regarding  alerting of the users terminal function, inter-
working   with a non-ISDN network, or routing progress.



	CONNECT	  Interaction across the "user/network" interface regarding  completion of circuit cut-through.



	DISCONNECT    Interaction across the "user/network" interface         

regarding a user who has disconnected or user A cannot be connected (e.g.  Busy) to user B.



	RELEASE	  Interaction across the "user/network" interface regarding                        freeing of resources 
associated with the call/connection,                        such as call references and channels.



	NDUB		  Network determined user busy.



	UDUB		  User determined user busy.