System Functions and Features as of I7.9
Features
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8. 2
Network services, authorizations and operation
8. 2. 1
ISDN services supported by the system
The system supports a whole series of ISDN supplementary services, which are pro-
vided by network providers in addition to ISDN bearer services.
8. 2. 1. 1
External services and internal features
In this document a distinction is made between features and services.
Features designate functions that are provided locally in the PBX.
Services designation functions that are offered at the network interfaces by the
public ISDN network provider and supported, i.e. used, by the PBX.
ISDN services are further differentiated into bearer services and supplementary
services.
A certain number of functions such as the three-party conference with two exter-
nal users can be carried out both externally in the public network and internally in
the PBX.
The example of a three-party conference is used to illustrate the interaction be-
tween the PBX and the public network.
Example of a three-party conference
The figures below show variants of three-party conferences with internal and ex-
ternal users.
The left-hand side of the figure below shows a conference set up in the PBX with
three internal users (three-party conference feature); the right-hand side shows a
conference in the public network with three exchange users (three-party confer-
ence supplementary service):
Fig. 158
Conference circuit feature and three-party conference supplementary service
A
PBX
B
C
haz1225aaena0
ISDN
C
A
B
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