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Recommendation Q.81
NUMBER IDENTIFICATION SUPPLEMENTARY SERVICES
Contents
1. Direct Dialling In (DDI)
2. Multiple subscriber number (under study)
3. Calling Line Identification Presentation (CLIP)
4. Calling Line Identification Restriction (CLIR)
5. Connected Line Identification Presentation (COLP)
6. Connected Line Identification Restriction (COLR)
7. Malicious call identification (under study)
*
* *
Recommendation Q.81
NUMBER IDENTIFICATION SUPPLEMENTARY SERVICES
1. Direct Dialling In (DDI)
1.1 Definition
Direct Dialling In (DDI) enables a user to call directly another user
on a ISPBX or other private system without attendant intervention.
1.2 Description
1.2.1 General description
A part of the ISDN number, which is significant to the user, is passed
to the user. This supplementary service is based on the use of the ISDN number
and does not include sub-addressing.
Note - A similar method to select a terminal on a passive bus is described in
the Stage 1 description of the supplementary service MSN.
Note - The caller may or may not find the ISDN number in the public directory.
Recommendation E.164 provides the flexibility for administrations to
use national numbering plans of fixed or variable number lengths. This
flexibility also applies to DDI numbers, i.e. even within a given PABX DDI numbers of
different lengths may appear.
The number of digits used by a PABX supporting the DDI feature is not
necessarily known by their serving local exchange nor by any other entity of the
public network.
The DDI number (fixed or variable length) is sent en-bloc or by over-
lap sending from the exchange to the PABX or other private system which finally
and automatically establishes a connection to the destination without the
assistance of an operator.
1.2.2 Qualifications on the applicability to Telecommunication Services
No restrictions.
1.3 Derivation of a functional model (Step 1)
1.3.1 Functional model description
Two functional models are used to show the different requirements
of DDI.
Functional model 1 represents the situation where DDI is used to
address a terminal on a single ISPBX connected to the public network.
Functional model 2 describes the situation where DDI is used to address
a terminal within a private network consisting of several PBXs.
Although functional model 1 can be seen as a special application of
model 2 it is preferred to describe the two models independently to show different
situations more clearly.
FIGURE 1-1/Q.81
Two functional models for DDI
1.3.2 Description of the functional entities
FE1: Call control agent of the calling user
FE2: Call control entity of the calling user
FE3: DDI Access control to the private network (located in the public network)
FE4: DDI Service control for the called user and access control in the private
network
FE5: Call control agent of the called user
FE6: DDI Access control in the private network
FE7: DDI Service control in the private network for the called user.
1.3.3 Relationship to basic service
The call setup procedures in the public network are mainly the same as
for the basic service.
FE1 and FE2 therefore have the same functionality as CCA and CC. r1
and r2 correspond to r1 and r2 in the basic service.
FE3 includes specific functionality of DDI in the relationship r3.
FE4, FE6 and FE7 are entities in a private network that are only
specified here as far as they are influenced by r3. The same applies for r4 and r5.
1.4 Information flow diagrams (Step 2)
1.4.1 Diagrams
The diagrams for model 1 are shown in Figure 1-2/Q.81.
Insert diagram
1.4.1.1 Diagrams for model 2
Insert diagram
Notes
2a) Optional signalling information which may be used to acknowledge
seizure and/or for B channel negotiation.
2b) Optional signalling information which may be used to indicate
complete address information.
2c) If not already sent, this signalling information may be sent to
the originating user to indicate complete address information.
2d) If the PABX recognizes the receipt of complete address
information, this signalling information may be sent.
2e) On receipt of complete address information, this signalling
information may be generated by the sub-PABX. If already sent by the
PABX, it will not be transferred to the originating user.
3) Instead of ALTERTING, a CONNECT signalling information may be sent
directly in case of an automatically responding terminal.
4) Optional early switch through of backward transmission path.
1.4.2 Definitions
The definitions for ACK, ADDRESS INFO, PROCEEDING, REPORT and SETUP are
the same as for the basic service.
1.4.2.1.1 Meaning of [PROGRESS]
PROGRESS can be sent from the entity serving the called user to indicate
that sufficient ADDRESS INFO was received to address a user terminal or access
line. It is an unconfirmed information flow.
1.4.2.2.1 Information content of [PROGRESS]
B-channel information in r3 if not yet included in a previous sent
information element.
1.5 SDL diagrams of functional entities (Step 3)
SDL diagrams are provided for FE3 covering the aspects of both functional
models and giving the relation between r2 and r3. FE1 and FE2 are, as said,
already covered by the basic procedures so that all aspects of DDI, that are relevant
for the public network, are covered in these diagrams.
In the SDL diagrams only those procedures are described that deviate from
the basic procedures.
Note 1 - Through connection is generally only done when the setup confirmation
is received from the called user. This is described in option A.
In specific national applications through connection may already be done
in an earlier point in time. This is covered in options B1 or B2 and requires
further considerations.
Note 2 - Negotiation of a B channel is not necessarily an independent
information flow. It can be combined with the first backward information flow that is
required for call control. This information flow can be PROGRESS, REPORT (alerting) or
SETUP.
1.6 Functional entity actions (Step 4)
1.6.1 Specific actions in FE3
1.6.1.1 Channel selection
Negotiation for the selection of a B-channel will be permitted between
the network and the PABX. The selection procedure is as follows:
a) in the SETUP Request, the network will indicate one of the
following:
1) channel is indicated, no acceptable alternative; or
2) channel is indicated, any alternative is acceptable; or
3) any channel is acceptable.
b) In cases 1) and 2), if the indicated channel is acceptable and
available, the PABX selects it for the call.
In case 2), if the PABX cannot grant the indicated channel, it
selects any other available B-channel and identifies
that channel in the first information sent in response
to the SETUP Indication.
In case 3), the PABX selects any available B-channel and
identifies that channel in the first information sent
in response to the SETUP Indication.
c) If no channel identification information element is present in
the first response, the B-channel indicated in the SETUP Request
will be assumed.
If the B-channel indicated in the first response is unacceptable
to the network, it will clear the call.
d) When a B-channel has been selected by the PABX that channel may
be connected by the PABX.
e) In case 1), if the indicated B-channel is not available, or in
cases 2), 3), if no B-channel is available and the PABX cannot
proceed with the offered call, the PABX clears the call.
The preferred solution for B-channel selection is alternative 1):
B-channel is selected by exchange B.
1.6.1.2 Through connection
The general time for through connection in FE3 is, when setup is
confirmed by the called user. This prevents fraudulent use of the connection
without charging.
As a consequence of this procedure all tones and announcements during
call setup have to be generated in the public network.
As an alternative some network providers may allow for an early through
connection.
1.6.2 Specific actions in FE6 and FE7
1.6.2.1 Through connection
In case of an ISDN terminal or sub-PABX connected to the PABX, the
through connection of the B-channel in the PABX is done with the sending of SETUP to
the terminal/sub-PABX. In the sub-PABX the through connection is done with the
sending of SETUP to the terminal. In the terminal the through connection is done at
the receipt of CONNECT ACKNOWLEDGE from the PABX/sub-PABX.
In case of an analogue terminal connected to the ISDN PABX/sub-PABX the
through connection of the B-channel in the terminal is done with the sending of
CONNECT to the ISDN PABX/sub-PABX. In the ISDN PABX/sub-PABX the through connection
is done at the receipt of SETUP Confirmation from the terminal. Note that this
case is for further study.
1.7 Allocation of functional entities to physical locations
The mapping between functional entities and their possible physical
locations is given in the following matrix.
┌───────────────────────────────────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┐
│ Functional entities│ │ │ │ │ │ │ │
│ Scenario │ FE1 │ FE2 │ FE3 │ FE4 │ FE5 │ FE6 │ FE7 │
├───────────────────────────────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
│ Call to ISPBX │ TE │ LE │ LE │ NT2 │ TE │ - │ - │
├───────────────────────────────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
│ Call to private network │ TE │ LE │ LE │ - │ TE │ NT2 │ NT2 │
└───────────────────────────────────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┘
2. Multiple subscriber number
Under study.
3. Calling Line Identification Presentation (CLIP)
3.1 General
Calling line identification presentation (CLIP) is a supplementary
service offered to the called party which provides the calling party's ISDN number,
possibly with sub-address information, to the called party.
3.2 Description
3.2.1 General description
When CLIP is applicable and activated, the network provides the called
party with the number of the calling party at call setup on all incoming calls.
The calling party number may be accompanied by a sub-address.
The network should be capable of transmitting at least 15 digits (maximum
length of an ISDN number). In addition, if provided by the calling party, the
network should be capable of transmitting a sub-address. The length of the sub-address is defined in the relevant Recommendation.
The network to which the calling party belongs should attempt to ensure
that enough digits are transmitted to enable the called party to return the call,
based on the calling number presented.
3.2.2 Specific terminology
None identified.
3.2.3 Qualifications on the applicability to telecommunication services
This supplementary service is applicable to all telecommunication
services.
It is to be noted that in the Telematic services, an exchange of terminal
identification (TID) occurs at a higher layer subsequent to a successful call
establishment.
For Telematic services this supplementary service shall consist only of
the access number of the calling party and this shall be provided by the network.
For other non-voice services this supplementary service is for further study. The
presentation of the CLI by Telematic terminals and by other non-voice terminals
is for further study.
3.3 Derivation of a functional model
This part of the description is common with the service calling line
identification restriction since this service has some impact on calling line
identification presentation.
The model used for illustrating the calling line identification services
procedures is given below:
User A User B
1 2 3 4
FE 1 FE 2 FE 3 FE 4 FE 5
Call Call Call Call Call
Control Control Control Control Control
Agent Functions Functions Functions Agent
Functions Functions
CCA CC CC CC CCA
3.4 Information flow diagrams
The calling line identity information needed to provide the calling line
identification services is normally carried in the messages used to establish the
call.
The calling line identity will be delivered to the called party by his
local exchange and/or ISPBX during the call establishment if the calling line
identity is available and presentation is allowed.
If calling line identity is not available in the destination local or
transit exchange at call request, the exchange may optionally request the calling
line identity from the originating local exchange.
The specifications of functions for Calling Line Identification include
adaptions for private network implementations (in a full private network
environment) and mobile network implementations. Private Network/Public ISDN interworking
situations are for further study.
The calling line identity is made up of a number of information units:
- the subscriber's national (ISDN) number, or
- private network (ISDN) number, or
- international ISDN number and possibly other indications only for
international calls, or
- partial number (optional) (Note 2);
- optionally, sub-address information, if explicitly provided by
the calling user;
- numbering plan identification;
- type of address.
In addition to the calling identity the subscriber may be given the
following information:
- Presentation indicator (PI) showing:
a) presentation allowed, or
b) presentation restricted, or
c) number not available due to interworking (Note 1)
- Screening indicator (SI) showing:
a) user provided, verified and passed, or
b) network provided
──────────
Note 1 - The technical solutions for the various interworking arrangements with
dedicated networks have not been detailed in this document.
Note 2 - For international calls the partial number may be the international
prefix and the country code. For national calls the partial number may be the trunk
prefix and the area code.
* In case of a national call this setup is sent to a national trunk exchange or
LE-B; FE3 is not needed.
FIGURE 6-1/Q.81
Calling line identification presentation (CLIP) - Stage 2
Information flows for combined public and private configurations
FIGURE 6-2/Q.81
Calling line identification presentation (CLIP) - Stage 2
Private network
Note 1 - The information flow contains:
- no information (should not be permitted for DDI-ISPBX in some
networks);
- part of the subscriber number (extension number, selection on a
passive bus);
- subscriber number;
- national number indicators;
- international number (for mobile application);
- numbering plan identification;
- type of address;
- presentation indicator (optional). Optional: sub-address.
Note 2 - The information flow contains:
- national number;
- if present: sub-address;
- international number;
- presentation indicator (allowed/restricted/not available due to
interworking);
- screening indicator (network provided/subscriber provided,
verified and passed);
- type of address;
- numbering plan identification.
Note 3 - The information flow contains:
- international number;
- no information (e.g. presentation restriction)
- if present: sub-address;
- presentation indicator (allowed/restricted/not available due to
interworking);
- screening indicator (network provided/subscriber provided,
verified and passed);
- type of address;
- numbering plan identification.
Note 4 - The information flow contains:
- no information;
- national number (for national calls);
- international number (for international calls);
- if present: sub-address;
- presentation indicator (allowed/restricted/not available due to
interworking);
- screening indicator (network provided/subscriber provided,
verified and passed);
- type of address;
- numbering plan identification.
Note 5 - The information flow contains:
- no information;
- part of the extension number (e.g. selection on a passive bus);
- extension number or private network number;
- optional: sub-address;
- type of address;
- numbering plan identification.
Note 6 - The information flow contains:
- extension number or private network number;
- if present: sub-address;
- presentation indicator (allowed/restricted/not available due to
interworking);
- screening indicator (network provided/subscriber provided,
verified and passed);
- type of address;
- numbering plan identification.
3.5 SDL diagrams for functional entities
FE 2 - Determination of the calling line identity - originating side
The ability of an ISDN component to determine the calling line identity
and if present, the sub-address. In public network the calling line identity is
the national ISDN number, in private network the private network number and in
mobile network the international ISDN number.
FE 3 - Determination of the international calling line identity
The ability of an ISDN component to determine the international calling
line identity and if present, the sub-address.
FE 4 - Determination of the calling line identity - destination side
The ability of an ISDN component to determine the calling line identity
and if present, the sub-address. In some networks the calling line identity given
to an extension user connected to an ISPBX shall include outgoing prefix if the
call is originated or passed through the public network.
FIGURE 6-3/Q.81
FE2
CL = Calling line
PI = Presentation indicator
SI = Screening indicator
FIGURE 6-4/Q.81 (2 of 2)
FE3
CL = Calling line
PI = Presentation indicator
SI = Screening indicator
FIGURE 6-5/Q.81
Notes to Table
Note A - No information about the identity of the calling party is sent to the
called party.
Note B - Set PI - Presentation restricted, address information will not be
presented to the called party.
Note 1 - Presentation may be restricted due to national regulations or
presentation restriction.
Presentation restriction may be overridden due to the called party's
category (e.g. police).
Note 2 - The request option is not supported by private networks (CL identity is
always included). The request option is not defined by Study Group XVIII.
Note 3 - In the case where the address information is not available due to
interworking, only the indicators are presented to the user.
3.6 Functional entity actions
3.6.1 Functional entity actions for FE 2
- Check if calling line identity is provided from the user;
- verify (and complete) calling line identity;
- set PI and SI;
- set type of number.
3.6.2 Functional entity actions for FE 3
- Check if calling line identity may be passed between
administrations;
- at the originating side: provide international number;
- at the destination side: add international prefix.
3.6.3 Functional entity actions for FE 4
- Check CLIP subscription;
- check if calling line identity is provided from FE3;
- request the calling line identity (optional);
- check for CLIR and if presentation is allowed pass CLI to FE5.
3.7 Allocation of functional entities to physical location
┌─────────────────────────────┬──────┬──────┬──────┬──────┬──────┐
│ Functional│ │ │ │ │ │
│ entity │ FE 1 │ FE 2 │ FE 3 │ FE 4 │ FE 5 │
│Scenario │ │ │ │ │ │
├─────────────────────────────┼──────┼──────┼──────┼──────┼──────┤
│ │ │ │ │ │ │
│National call │ TE │ LE │ │ LE │ TE │
├─────────────────────────────┼──────┼──────┼──────┼──────┼──────┤
│International call │ TE │ LE │ TR │ LE │ TE │
├─────────────────────────────┼──────┼──────┼──────┼──────┼──────┤
│Call between NT2s │ NT2 │ LE │ (TR) │ LE │ NT2 │
├─────────────────────────────┼──────┼──────┼──────┼──────┼──────┤
│Call between NT2 - TE │ NT2 │ LE │ (TR) │ LE │ TE │
├─────────────────────────────┼──────┼──────┼──────┼──────┼──────┤
│National private network │ TE │ NT2 │ │ NT2 │ TE │
├─────────────────────────────┼──────┼──────┼──────┼──────┼──────┤
│International private network│ TE │ NT2 │TR/NT2│ NT2 │ TE │
└─────────────────────────────┴──────┴──────┴──────┴──────┴──────┘
Note - (TR) means that this functional entity is included in the case of
international calls.
4. Calling Line Identification Restriction (CLIR)
4.1 General
Calling line identification restriction (CLIR) is a supplementary
service offered to the calling party to restrict presentation of the calling
party's ISDN number and sub-address to the called party.
4.2 Description
4.2.1 General description
When CLIR is applicable and activated the originating node provides the
destination node with a notification that the calling party's ISDN number and
any sub-address information is not allowed to be presented to the called party. In
this case no calling party number is included in the call offering to the called
party's installation.
Note - When CLIR is subscribed to, some network providers may not wish to send
the originating identity of the calling customer to other network providers.
Calling line identification restriction includes two options:
i) presentation restriction for all calls;
ii) temporary presentation restriction.
The presentation indicator is included in the SETUP req. ind.
Information Flow received from the calling user. When no indicator is
present a default value is used as follows.
The presentation indicator is stored in the public network (local
exchange) as a default value for each user. The default value may be
"presentation allowed" or "presentation restricted". This default value may be
changed only by the network provider.
The first option is considered a minimum implementation.
The second option gives the calling user a possibility on a per call
basis to override the default presentation indicator value stored in the
public network. This option may be available on a subscription basis or generally.
4.2.2 Specific terminology
None identified.
4.2.3 Qualifications on the applicability to telecommunication services
None identified; i.e., this supplementary service is applicable to all
telecommunication services.
The service calling line identification restriction has impact on the
service calling line identification presentation, and therefore, the rest of
the description is common for the two services. This part is presented in the
CLIP description.
5. Connected Line Identification Presentation (COLP)
5.1. General
Connected Line Identification Presentation (COLP) is a supplementary
service offered to the calling party which provides the connected party's
ISDN-number to the calling party.
5.2 Description
5.2.1 General description
When COLP is applicable and activated, the network provides the calling
party with the number of the connected party when the called party responds
positively to the incoming call. The network should be capable of transmitting at
least 15 digits (maximum length of an ISDN number).
5.2.2 Specific terminology
None identified.
5.2.3 Qualifications on the applicability to telecommunication services
This supplementary service is applicable to all telecommunication
services.
It is to be noted that in the Telematic services, an exchange of Terminal
Identification (TID) occurs at a higher layer subsequent to a successful call
establishment.
For Telematic services, this supplementary service shall consist only of
the access number of the connected party and this shall be provided by the
network. For other non-voice services, this supplementary service is for further study.
The presentation of the COLI by Telematic terminals and by other non-voice
terminals is for further study.
5.3 Derivation of a functional model
This part of the description is common with the service Connected Line
Identification Restriction (COLR) since this service has some impact on Connected
Line Identification Presentation.
The model used for illustrating the "Connected Line Identification
Services" procedures is given in Figure 5-1/Q.81 below.
FIGURE 5-1/Q.81
Model for Connected Line Identification Services
5.4 Information flow diagrams
The Connected Line Identity information needed to provide the Connected
Line Identification Services is normally carried in the messages indicating that
the call has been answered.
The original Connected Line Identity will be delivered to the calling
party by his local exchange and/or ISPBX when the call enters the active state if
the Connected Line Identity is available and presentation is allowed.
If Connected Line Identity is not available in the originating local or
transit exchange at call connection time, the exchange may optionally request the
Connected Line Identity from the destination local exchange.
The specifications of functions for COLP include adaptions for private
network applications (in a full private network environment) and mobile network
applications. Private Network/Public ISDN interworking situations are for further
study.
The Connected Line Identity is made up of a number of information units:
- the subscriber's national (ISDN) number, or
- private network number, or
- international ISDN-number and possibly other indications only for
international calls, or
- partial number (optional) (Note 2);
- optionally, sub-address information, if explicitly provided by the
calling user;
- numbering plan identification;
- type of address.
In addition to the Connected Line Identity, the subscriber may be given
the following information:
- Presentation Indicator showing:
a) presentation allowed, or
b) presentation restricted, or
c) number not available due to interworking (Note 1);
- Screening Indicator showing:
a) User provided, verified and passed, or
b) network provided.
Note 1 - The technical solutions for the various interworking arrangements with
dedicated networks have not been detailed in this Recommendation.
Note 2 - For international calls, the partial number may be the international
prefix and the country code. For national calls, the partial number may be the
trunk prefix and the area code.
In case of a national call, the FE3 is not needed.
FIGURE 5-2/Q.81
Information flows for combined public and private configurations
FIGURE 5-3/Q.81
Information flows for private network configurations
Note 1 - The information flow contains:
- no information (should not be permitted for DDI-ISPBX in some
networks);
- part of the subscriber number (extension number, selection on a
passive bus);
- subscriber number;
- national number;
- international number (for mobile applications);
- numbering plan identification;
- type of address;
- presentation indicator;
- optional: sub-address.
Note 2 - The information flow contains:
- national number;
- if present: sub-address;
- international number;
- presentation indicator (allowed/restricted/not available due to
interworking);
- screening indicator (network provided/subscriber provided, verified
and passed);
- type of address;
- numbering plan identification.
Note 3 - The information flow contains:
- international number;
- no information (e.g., presentation restriction);
- if present: sub-address;
- presentation indicator (allowed/restricted/not available due to
interworking);
- screening indicator (network provided/subscriber provided);
- type of address;
- numbering plan identification.
Note 4 - The information flow contains:
- no information (depending on indicators);
- national number (for national calls);
- international number (for international calls);
- if present: sub-address;
- presentation indicator (allowed/restricted/not available due to
interworking);
- screening indicator (network provided/subscriber provided, verified
and passed);
- type of address;
- numbering plan identification.
Note 5 - The information flow contains:
- no information;
- part of the extension number (e.g., selection on a passive bus);
- extension number or private network number;
- optional: sub-address;
- type of address;
- numbering plan identification.
Note 6 - The information flow contains:
- extension number or private network number;
- if present: sub-address;
- presentation indicator (allowed/restricted/not available due to
interworking);
- screening indicator (private network provided/user provided,
verified and passed);
- type of address;
- numbering plan identification.
5.5 SDL diagrams for functional entities
FE4 - Determination of the Connected Line Identity - Destination side
The ability of an ISDN component to determine the Connected Line Identity
and if present, the sub-address. The Connected Line Identity may contain
prefixes. In public network, the Connected Line Identity is the national ISDN Number, in
private network the private Network Number and in mobile network the
International ISDN Number.
FE3 - Determination of the International Connected Line Identity
The ability of an ISDN component to determine the International Connected
Line Identity and if present, the sub-address.
FE2 - Determination of the Connected Line Identity - Originating side
The ability of an ISDN component to determine the Connected Line Identity
and if present, the sub-address. In some networks, the Connected Line Identity
sent to an extension connected to an ISPBX shall contain the outgoing prefix.
FIGURE 5-4/Q.81
FE4 - Determination of the connected line identity -
destination side
FIGURE 5-6/Q.81 (1 of 2)
FE3 - Determination of the international connected
line identity
FIGURE 5-6/Q.81 (2 of 2)
FE3 - Determination of the international connected
line identity
FIGURE 5-7/Q.81
FE2 - Determination of the connected line
identity - originating side
5.6 Functional entity actions
5.6.1 Functional entity actions for FE2
- Check COLP subscription;
- check if Connected Line is provided;
- request Connected Line Identify (optional);
- check for COLR and if presentation allowed, pass COLI to FE1.
5.6.2 Functional entity actions for FE3
- Check if Connected Line Identity may be passed between
administrations;
- at the destination side: provide international number;
- at the originating side: add international prefix.
5.6.3 Functional entity actions for FE4
- Check if Connected Line Identity is provided from the user;
- verify (and complete) Connected Line Identity;
- set PI and SI;
- set type of number.
5.7 Allocation of functional entities to physical location
┌───────────────────────────────┬──────┬──────┬───────┬──────┬──────┐
│ Functional Entity │ FE 1 │ FE 2 │ FE 3 │ FE 4 │ FE 5 │
│ │ │ │ │ │ │
│ Scenario │ │ │ │ │ │
├───────────────────────────────┼──────┼──────┼───────┼──────┼──────┤
│ National Call │ TE │ LE │ │ LE │ TE │
│ │ │ │ │ │ │
│ International Call │ TE │ LE │ TR │ LE │ TE │
│ │ │ │ │ │ │
│ Call between NT2s │ NT2 │ LE │ (TR) │ LE │ NT2 │
│ │ │ │ │ │ │
│ Call between NT2 - TE │ NT2 │ LE │ (TR) │ LE │ TE │
│ │ │ │ │ │ │
│ National Private Network │ TE │ NT2 │ │ NT2 │ TE │
│ │ │ │ │ │ │
│ International Private Network │ TE │ NT2 │ TR/NT2│ NT2 │ TE │
└───────────────────────────────┴──────┴──────┴───────┴──────┴──────┘
Note - (TR) means that this Functional Entity is included in the case of
international calls.
6. Connnected Line Identification Restriction (COLR)
6.1 General
Connected Line Identification Restriction (COLR) is a supplementary
service offered to the connected party to restrict presentation of the connected
party's ISDN number to the calling party.
6.2 Description
6.2.1 General description
When COLR is applicable and activated, the destination node provides the
originating node with a notification that the connected party's ISDN number is
not allowed to be presented to the calling party. In this case no connected party
number is included in the call connected information to the calling party's
installation.
Note - When COLR is subscribed to, some network providers may not wish to send
the identity of the connected customer to other network providers.
Detailed descriptions of functions and information flows
Connected line identification restriction includes two options:
i) presentation restriction for all calls;
ii) temporary presentation restriction.
The presentation indicator is included in the SETUP conf. resp.
Information Flow received from the called user. When no indicator is present, then a
default value is used as follows.
The presentation indicator is stored in the public network (local
exchange) as a default value for each user. The default value may be "presentation
allowed" or "presentation restricted". This default value may be changed only by the
network provider.
The first option is considered a minimum implementation.
The second option gives the user who receives (and accepts) the call, a
possibility on a per call basis to override the default presentation indicator
value stored in the public network. This option may be available on a subscription
basis or generally.
The service connected line identification restriction has impact on the
service connected line identification presentation, and therefore, the rest of the
description is common for the two services. This part is presented in the COLP
description.
6.2.2 Specific terminology
None identified.
6.2.3 Qualifications on the applicability to telecommunications services
None identified; i.e., this supplementary service is applicable to all
telecommunication services.
7. Malicious call identification
Under study.
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