5 Handling of completion of calls to busy subscriber

03.933GPPStage 2Technical realization of Completion of Calls to Busy Subscriber (CCBS)TS

Registration and erasure of CCBS are not applicable. Activation and Invocation of CCBS are intrinsic parts of the operation of the service, and are described in this section.

5.1 CCBS Timers

The timers used to control the operation of CCBS can be considered to consist of two groups i.e. the timers which operate on a per subscriber basis (see table 1) and the service duration timers (T3 and T7) which operate on a per CCBS Request basis (see table 2).

Table 1: CCBS Service Timers

Timer

Name

Value

Run At

Started

Stopped

Expiry

T1

Retention

>15s

MSC A

Busy (CCBS Possible) sent to MS A

CCBS Request received from MS A

Discard retained information

T4

Recall

20-30s

MSC A

CCBS Recall sent to MS A and MS A is idle

Subscriber A initiates CCBS setup or rejects CCBS Recall

Cancel request

T8

Destination idle guard

0-15s

HLR B

Event Report received from VLR B indicating destination B is idle

Event Report received from VLR B indicating destination B is no longer idle

Inform originating network that Destination B is free

T9

Recall B

40-55s

HLR B

Remote User Free sent to the A-side

Request cancelled, completed or suspended

Cancel request

T10

CCBS notification

20-30s

MSC A

CCBS Recall sent to MS A and MS A is not idle

Subscriber A initiates CCBS setup, rejects CCBS Recall or requests suspension

Suspend request

T11

CCBS resume

20-25s

HLR A

HLR A receives a resume request and there are more than one suspended request in subscriber A’s queue

Remote User Free received from destination network

Resume next suspended request in queue

T12

CCBS Call Guard

20-30s

HLRA

HLRA receives a CCBS RUF Ack and starts to wait CCBS Call Report

CCBS Call Report received

Cancel request

Table 2: Service Duration Timers

Timer

Name

Value

Run At

Started

Stopped

Expiry

T3

Originating service duration

15-45m

HLR A

Acknowledgement to CCBS Request received from destination network

Request cancelled or completed

Cancel request

T7

Terminating service duration

>45m

HLR B

HLR B acknowledges successful activation of a CCBS Request

Request cancelled or completed

Cancel request

5.2 Information flows

Figures 5.2.1 and 5.2.2 show the flow of information between network elements for a mobile to mobile call for the following:

Figure 5.2.1: Successful CCBS request, destination B busy when request made, subscriber A free when destination B becomes free.

Figure 5.2.2: Subscriber A is not idle when destination B becomes free.

Figures 5.2.3 and 5.2.4 show the flow of information between network elements for a mobile to fixed call for the same situations described in figures 5.2.1 and 5.2.2 respectively.

Each information flow diagram has been divided where appropriate into four distinct phases of operation. These are as follows:

(1) Pre-conditions (Initial Call encountering NDUB and CCBS possible in the destination network). The detailed description of the basic call handling can be found in GSM 03.18;

(2) Activation;

(3) Invocation;

(4) Operation (CCBS Call Set-up).

Figure 5.2.1: Successful CCBS request. Destination B busy when request activated, subscriber A free when destination B becomes free (mobile-to-mobile)

Figure 5.2.2: Subscriber A not idle when destination B becomes free (mobile-to-mobile);
Processing of a single request

Figure 5.2.3: Successful CCBS request. Destination B busy when request activated, subscriber A free when destination B becomes free (mobile-to-fixed)

Figure 5.2.4: Subscriber A not idle when destination B becomes free (mobile-to-fixed)

5.3 Activation

Activation of a CCBS Request is carried out by subscriber A. VLR A is considered to be transparent during the activation operation.

The information flows shown in figures 5.2.1 to 5.2.4 inclusive show the information flow for the activation process.

5.4 Deactivation

Subscriber A may deactivate CCBS in any of the following ways:

– Deactivate all outstanding CCBS requests; or

– Deactivate a specific CCBS Request.

The different deactivation operations are identified by different MMI commands as specified in GSM 02.30.

Deactivation of CCBS requests by subscriber A shall be performed at HLR A.

To deactivate all outstanding CCBS requests, the Deactivate CCBS operation request shall contain the SS-Code only.

To deactivate a specific CCBS request, the Deactivate CCBS operation request shall contain the following parameters:

– SS-Code;

– CCBS Index.

On receipt of the deactivation request, HLR A shall cancel the CCBS request, i.e. remove all record of a CCBS request from the subscriber A’s originating CCBS queue and instruct the destination B network to cancel the corresponding CCBS request in the destination CCBS queue of subscriber B. HLR A shall return a result indicating whether the deactivation attempt was successful or not.

MS A

MSC A

VLR A

HLR A

Destination B Network

Deactivate CCBS

——————->

Deactivate CCBS

———————>

Deactivate CCBS

——————->

CCBS Cancel

——————->

(note)

Acknowledge

<——————-

Acknowledge

<——————–

Acknowledge

<———————

NOTE: CCBS Cancel shall be sent for each CCBS Request that is cancelled in HLR A.

Figure 5.4.1: Successful deactivation of all CCBS Requests/a specific CCBS request

NOTE: In the case where a subscriber attempts to perform a deactivation operation but the subscriber is not provisioned with the CCBS service then, the subscriber shall receive an indication that the CCBS service is not provisioned for him.

5.5 Interrogation

Interrogation of CCBS shall be carried by request to HLR A. HLR A then returns the required information or error to MS A, see figure 5.5.1. MSC A and VLR A are considered to be transparent during the interrogation operation.

MS A

MSC A

VLR A

HLR A

Interrogate CCBS

——————————>

Interrogate CCBS

—————————–>

Interrogate CCBS

——————————->

Acknowledge

<——————————-

Acknowledge

<—————————–

Acknowledge

<——————————–

Figure 5.5.1: General interrogation of completion of calls to busy subscriber

The Interrogate CCBS operation request shall contain the SS-Code only.

In response to a general interrogation, MS A shall be given the AddressOfB, BasicServiceCode and CCBS index for each CCBS Request in the queue. The entries shall be ordered in the chronological order, the oldest entry shall be presented first.

If there are no CCBS Requests in the queue, MS A shall be given an indication that no entries exist in the queue.

NOTE: In the case where a subscriber attempts to perform an interrogation operation but the subscriber is not provisioned with the CCBS service then, the subscriber shall receive an indication that the CCBS service is not provisioned for him.

5.6 Messages and their contents

This clause contains the detailed description of the information flows used by CCBS.

Each Information Element, IE is marked as (M) Mandatory, (C) Conditional or (O) Optional. A mandatory information element shall always be present. A conditional information shall be present if certain conditions are fulfilled; if those conditions are not fulfilled it shall be absent. An optional information element may be present or absent, at the discretion of the application at the sending entity. This categorisation is a functional classification, i.e., stage 2 information and not a stage 3 classifications to be used for the protocol.

The stage 2 and stage 3 message and information element names are not necessarily identical.

5.6.1 Information elements used in the messages

In this clause constructed information elements are described.

5.6.1.1 Call Information information element

Call Information information element is formed in the MSC A during the CCBS activation. This information element contains unmodified copy of the SETUP message received from the MS A. If CCBS Request is activated, the Call Information is stored in the HLR A. During CCBS Recall Call Information is relayed back to the MS. Refer to SETUP Container information element defined in GSM 04.08.

5.6.1.2 AddressOfB information element

AddressOfB information element is formed in the MSC A during the CCBS activation. It contains the number of the destination B dialled by the A-user.

Table 5.6.1.2: Structure of AddressOfB information element

Parent Information Element

Child Information element name

Information element Required

Information element description

AddressOfB

B subscriber number,

B subscriber subaddress

M

C

The number of the destination B dialled by the A-user;

Shall be present if it was dialled by the A-user;

otherwise shall be absent

5.6.1.3 CCBS Description information element

CCBS Description information element is formed in the HLR A during the CCBS activation.

Table 5.6.1.3: Structure of CCBS Description information element

Parent Information Element

Child Information element name

Information element Required

Information element description

CCBS Description

CCBS Index,

AddressOfB,

BasicServiceGroup

M

M

M

CCBS Index (range 1 – 5) identifies the request in the network.

The structure of the AddressOfB is defined in table 5.6.1.2;

BasicServiceGroup related to the original call.

5.6.2 Messages between MS and MSC

These messages are used in the originating network.

Table 5.6.2: Messages between MS and MSC

Message

Message sender

Information element name

Information element Required

Information element description

CCBS POSSIBLE

MSC

This message contains no information elements.

CCBS REQUEST

MS

This message contains no information elements.

CCBS REQUEST ACK

MSC

CCBS Index,

AddressOfB,

BasicServiceGroup

M

O

O

CCBS Index (range 1 – 5) identifies the request in the network.

The structure of the AddressOfB is defined in table 5.6.1.2

BasicServiceGroup related to the original call.

CCBS REQUEST ERROR

MSC

Error

M

The information element can take the following values:

– Short term denial

– Long term denial

DEACTIVATE CCBS

MS

CCBS Index

C

If CCBS Index is present the corresponding request shall be deleted, otherwise all requests shall be deleted.

DEACTIVATE CCBS ACK

MSC

DeactivateResult

M

The information element can take the following values:

– Success

– Not Provisioned

INTERROGATE CCBS

MS

This message contains no information elements.

INTERROGATE CCBS ACK

MSC

List(1-5) of CCBS Description;
No Entries;

Not Provisioned

C

C

C

The list shall contain one entry for each CCBS Request for which the HLR stores data or;

the queue is empty or;

CCBS is not provisioned for the subscriber

Exactly one of these information elements shall be present. The structure of the CCBS Description is defined in table 5.6.1.3.

CCBS CALL INFO

MSC

Call Information

M

The content of the Call Information is defined in the subclause 5.6.1.1.

CCBS CALL INFO ACK

MS

GSM BC

M

GSM BC indicates the BC the MS prefers to use. The network may allocate a traffic channel accordingly.

CCBS CALL INFO ERROR

MS

Error

M

The information element can take the following values:

– Incompatible Terminal

CCBS RECALL

MSC

CCBS Description,

Alerting Pattern

M,

C

The structure of the CCBS Description is defined in table 5.6.1.3.

Alerting Pattern shall be present if it was received in the CCBS RUF message

CCBS SETUP

MS

The content of the message is the same as the MO Set-up message has. Refer to GSM 04.08.

CCBS RECALL REJECT

MS

Cause

M

The MS shall indicate the reason of CCBS Recall rejection.

The information element can take the following values:

– Recall Rejected by the user

– UDUB

– ACMmax exceeded

5.6.3 Messages between MSC and VLR (B-interface)

5.6.3.1 Messages between MSC and VLR in the originating network

These messages are used in the originating network. Some messages are used also in the terminating network. They are marked accordingly.

Table 5.6.3.1: Messages between MSC and VLR in the originating network

Message

Message sender

Information element name

Information element Required

Information element description

CALL END

MSC

This message contains no information elements.

The message is used also in the terminating network.

CCBS CALL DELIVERY

MSC

Outcome

M

The information element indicates whether CCBS Call was successful or failure. It can take the following values:

– Success;

– Failure;

– NDUB;

– Busy;

– Absent Subscriber..

The message is used also in the terminating network.

CCBS REQUEST

MSC

This message contains no information elements

CCBS REQUEST ACK

VLR

CCBS Index,

AddressOfB,

BasicServiceGroup

M

O

O

CCBS Index (range 1 – 5) identifies the request in the network.

The structure of the AddressOfB is defined in table 5.6.1.2

BasicServiceGroup related to the original call.

CCBS REQUEST ERROR

VLR

Error

M

The information element can take the following values:

– Short term denial;

– Long term denial.

COMPLETE RECALL

VLR

Call Information

M

The content of the Call Information is defined in the subclause 5.6.1.1.

COMPLETE RECALL ACK

MSC

This message contains no information elements

COMPLETE RECALL NEGATIVE RESPONSE

MSC

Negative Response

M

The negative information element can take the following values:

– Absent Subscriber;

– Incompatible Terminal;

– Radio Congestion.

DEACTIVATE CCBS

MSC

CCBS Index

C

If CCBS Index is present the corresponding request shall be deleted, otherwise all requests shall be deleted.

DEACTIVATE CCBS ACK

VLR

DeactivateResult

M

The information element can take the following values:

– Success;

– Not Provisioned.

INTERROGATE CCBS

MSC

This message contains no information elements

Table 5.6.3.1: Messages between MSC and VLR in the originating network, cont.

Message

Message sender

Information element name

Information element Required

Information element description

INTERROGATE CCBS ACK

VLR

List(1-5) of CCBS Description;
No Entries;

Not Provisioned

C

C

C

The list shall contain one entry for each CCBS Request for which the HLR stores data; or

the queue is empty; or

CCBS is not provisioned for the subscriber.

Exactly one of these information elements shall be present. The structure of the CCBS Description is defined in table 5.6.1.3.

NOT IDLE

MSC

This message contains no information elements. The message is used also in the terminating network.

PAGE MS FOR RECALL

VLR

Location area ID,

TMSI

M

O

Location area in which the MS is to be paged

TMSI to be broadcast to identify the MS

PAGE MS FOR RECALL NEGATIVE RESPONSE

MSC

Negative Response

M

The negative information element can take the following values:

– Unknown LAI;

– Absent Subscriber;

– Busy Subscriber.

PROCESS ACCESS REQUEST

MSC

Refer to GSM 03.18

RADIO FAILURE

MSC

This message contains no information elements.

The message is used also in the terminating network.

RECALL

VLR

CCBS Description

Alerting Pattern

M

C

The structure of the CCBS Description is defined in table 5.6.1.3.

Alerting Pattern shall be present if it was received in the CCBS RUF message

RECALL ACK

MSC

Cause

M

The information element can take the following values:

– Accept;

– Rejected;

– T4 Expiry;

– T10 Expiry;

– Radio Failure;

– UDUB, busy;

– UDUB, idle;

– Incompatible terminal.

SEARCH FOR MS MSC FOR RECALL

VLR

This message contains no information elements

SEARCH FOR MS MSC FOR RECALL ACK

MSC

This message contains no information elements

SEARCH FOR MS MSC FOR RECALL NEGATIVE RESPONSE

MSC

Negative Response

M

The negative information element can take the following values:

– Absent Subscriber;

– Busy Subscriber;

SEND INFO FOR OUTGOING CALL

MSC

Refer to GSM 03.18

START STATUS ENQUIRY

VLR

This message contains no information elements.

The message is used also in the terminating network.

STATUS ENQUIRY RESULT

MSC

Status

M

The information element can take the following vales:

– CCBS Idle;

– CCBS Not Idle.

The message is used also in the terminating network.

STOP STATUS ENQUIRY

VLR

This message contains no information elements.

The message is used also in the terminating network.

5.6.3.2 Messages between MSC and VLR in the destination network

These messages are used in the destination network. Some messages are used also in the originating network. They are marked accordingly.

Table 5.6.3.2: Messages between MSC and VLR in the destination network

Message

Message sender

Information element name

Information element Required

Information element description

CALL END

MSC

Refer to table 5.6.3.1

CCBS CALL DELIVERY

MSC

Refer to table 5.6.3.1

START STATUS ENQUIRY

VLR

Refer to table 5.6.3.1

STATUS ENQUIRY RESULT

MSC

Refer to table 5.6.3.1

STOP STATUS ENQUIRY

VLR

Refer to table 5.6.3.1

RADIO FAILURE

MSC

Refer to table 5.6.3.1

NOT IDLE

MSC

Refer to table 5.6.3.1

COMPLETE CALL

VLR

Indicator

C

Refer to GSM 03.18

In addition:

The information element shall be present if the call is CCBS Call; otherwise it shall be absent.

PROCESS CALL WAITING

VLR

Indicator

C

Refer to GSM 03.18

In addition:

The information element shall be present if the call is CCBS Call; otherwise it shall be absent.

SEND INFO FOR

INCOMING CALL ACK

VLR

CCBS Target

C

Refer to GSM 03.18

In addition:

The information element shall be present if the B subscriber can be target of CCBS request; otherwise it shall be absent.

SEND INFO FOR

INCOMING CALL NEGATIVE RESPONSE

VLR

CCBS Target

C

Refer to GSM 03.18

In addition:

The information element shall be present if the B subscriber can be target of CCBS request; otherwise it shall be absent.

5.6.4 Messages between VLR and HLR (D-interface)

5.6.4.1 Messages between VLR and HLR in the originating network

These messages are used between VLR – HLR in the originating network. Some messages are used also in the destination network. They are marked accordingly.

Table 5.6.4.1: Messages between VLR and HLR in the originating network

Message

Message sender

Information element name

Information element Required

Information element description

CCBS REQUEST

VLR

Call Information

ISDN BC

ISDN HLC

ISDN LLC

Presentation Indicator

Translated B No

CAMEL Invoked

Basic Service Group

AddressOfB

M

M

C

C

C

M

C

M

M

The content of the Call Information is defined in the subclause 5.6.1.1.

ISDN BC derived for the initial call.

Shall be present if ISDN HLC was present in the initial call; otherwise shall be absent.

Shall be present if ISDN LLC was present in the initial call; otherwise shall be absent.

Shall be present if CLIR was invoked for the initial call;

otherwise shall be absent.

The number used for routing purposes stored in international E.164 format.

Shall be present if MO CAMEL was invoked in the initial call; otherwise shall be absent.

GSM Elementary Basic Service Group which corresponds to the basic service used for initial call set-up

The structure of the AddressOfB is defined in table 5.6.1.2

CCBS REQUEST ACK

HLR

CCBS Index

AddressOfB

Basic Service Group

M

O

O

CCBS Index (range 1 – 5) identifies the request in the network.

The structure of the AddressOfB is defined in table 5.6.1.2

BasicServiceGroup related to the original call.

CCBS REQUEST ERROR

HLR

Error

M

The information element can take the following values:

– Short term denial;

– Long term denial;

CCBS RUF

HLR

Call Information

CCBS Description

Translated B No

Replace B No

Alerting Pattern

M

M

M

C

C

The content of the Call Information is defined in the subclause 5.6.1.1.

The content of the CCBS Description is defined in table 5.6.1.3.

The number used for routing purposes in international E.164 format.

The information element shall be present if the HLR instructs the MSC to replace the destination B number with the translated B number; otherwise it shall be absent.

Alerting Pattern shall be present if the HLR has determined an alerting category or an alerting level for the CCBS recall

CCBS RUF ACK

VLR

Result

M

The information element indicates whether CCBS Recall was accepted. It can take the following values:

– RUF Accepted;

– RUF Rejected;

– T4 Expiry;

– T10 Expiry;

– UDUB, idle;

– UDUB, busy.

CCBS RUF ERROR

VLR

Error

M

The information element indicates the reason why CCBS Recall could not be successfully delivered. It can take the following values:

– IMSI Detached;

– Restricted Area;

– No Page Response;

– Incompatible Terminal;

– Absent Subscriber;

– Radio Failure;

– Ccomp Busy;

– System Failure.

Table 5.6.4.1: Messages between VLR and HLR in the originating network, cont.

Message

Message sender

Information element name

Information element Required

Information element description

EVENT REPORT

VLR

Status

M

The information element contains subscriber status. It can take the following values:

– CCBS Idle;

– CCBS Not Idle;

– CCBS Not Reachable.

The message is used also in the terminating network.

EVENT REPORT ACK

HLR

This message contains no information elements

The message is used also in the terminating network.

EVENT_REPORT_

ERROR

HLR

Error

M

The information element contains no application specific error values.

The message is used also in the terminating network.

START REPORTING

HLR

This message contains no information elements.

The message is used also in the terminating network.

START REPORTING ACK

VLR

Status

M

The information element contains subscriber status. It can take the following values:

– CCBS Idle;

– CCBS Not Idle;

– CCBS Not Reachable.

The message is used also in the terminating network.

START REPORTING ERROR

VLR

Error

M

The information element contains no application specific error values.

The message is used also in the terminating network.

CONTINUE MONITORING

HLR

This message contains no information elements.

The message is used also in the terminating network.

STOP REPORTING

HLR

This message contains no information elements.

The message is used also in the terminating network.

CCBS CALL REPORT

VLR

Mode

Outcome

Status

M

M

C

The information element indicates the reporting mode. It can take the following values :

– A;

– B.

The information element indicates the outcome of the CCBS Call. It can take the following values:

– Success;

– Busy (only for mode A);

– NDUB (only for mode B)

– Failure.

The information element contains subscriber status. It is set only for mode B. It can take the following values:

– CCBS Idle;

– CCBS Not Idle;

– CCBS Not Reachable.

The message is used also in the terminating network.

CCBS CALL REPORT ACK

HLR

This message contains no information elements.

The message is used also in the terminating network.

CCBS CALL REPORT ERROR

HLR

Error

M

The information element contains no application specific error values.

The message is used also in the terminating network.

DEACTIVATE CCBS

VLR

CCBS Index

C

If CCBS Index is present the corresponding request shall be deleted, otherwise all requests shall be deleted.

DEACTIVATE CCBS ACK

HLR

DeactivateResult

M

The information element can take the following values:

– Success;

– Not Provisioned.

DEACTIVATE CCBS ERROR

HLR

Error

M

The information element contains no application specific error values.

Table 5.6.4.1: Messages between VLR and HLR in the originating network, cont.

Message

Message sender

Information element name

Information element Required

Information element description

INTERROGATE CCBS

VLR

This message contains no information elements.

INTERROGATE CCBS ACK

HLR

List(1-5) of CCBS Description;

No Entries;

Not Provisioned

C

C

C

The list shall contain one entry for each CCBS Request for which the HLR stores data or;

the queue is empty or;

CCBS is not provisioned for the subscriber.

Exactly one of these information elements shall be present. The structure of the CCBS Description is defined in table 5.6.1.3.

INTERROGATE CCBS ERROR

HLR

Error

M

The information element contains no application specific error values.

5.6.4.2 Messages between VLR and HLR in the destination network

These messages are used between VLR – HLR in the destination network. Some messages are used also in the originating network. They are marked accordingly.

Table 5.6.4.2: Messages between VLR and HLR in the destination network

Message

Message sender

Information element name

Information element Required

Information element description

EVENT REPORT

VLR

Refer to table 5.6.4.1

EVENT REPORT ACK

HLR

Refer to table 5.6.4.1

EVENT REPORT ERROR

HLR

Refer to table 5.6.4.1

START REPORTING

HLR

Refer to table 5.6.4.1

START REPORTING ACK

VLR

Refer to table 5.6.4.1

START REPORTING ERROR

VLR

Refer to table 5.6.4.1

CONTINUE MONITORING

HLR

Refer to table 5.6.4.1

STOP REPORTING

HLR

Refer to table 5.6.4.1

CCBS CALL REPORT

VLR

Refer to table 5.6.4.1

CCBS CALL REPORT ACK

HLR

Refer to table 5.6.4.1

CCBS CALL REPORT ERROR

HLR

Refer to table 5.6.4.1

PROVIDE ROAMING NUMBER

HLR

CCBS Call Reporting Request

C

Refer to GSM 03.18

In addition:

The information element shall be present for CCBS Call roaming number enquiry; otherwise it shall be absent.

5.6.5 Messages between MSC and HLR (C-interface)

Table 5.6.5: Messages between MSC and HLR

Message

Message sender

Information element name

Information element Required

Information element description

SEND ROUTING INFO

MSC

CCBS Supported

CCBS Call Indicator

C

C

Refer to GSM 03.18

In addition:

The information element shall be present if GMSC supports CCBS; otherwise it shall be absent.

The information element shall be present, if SRI is for CCBS Call; otherwise it shall be absent.

SEND ROUTING INFO_ACK

HLR

CCBS Target

Keep CCBS Call Indicator

C

C

Refer to GSM 03.18

In addition:

The information element shall be present if the call is forwarded on busy and the subscriber B can be target of CCBS requests; otherwise it shall be absent.

The information element shall be present if the VMSC supports CCBS and SRI enquiry was for CCBS Call; otherwise it shall be absent.

SEND ROUTING INFO NEGATIVE RESPONSE

HLR

Negative Response

Refer to GSM 03.18

New value(s) for existing parameter(s):

– Busy_CCBS_Possible;

– Busy_CCBS_Not_Possible.

5.6.6 Messages between MSC – MSC (E-interface)

Table 5.6.6: Messages between MSC and MSC

Message

Message sender

Information element name

Information element Required

Information element description

RESUME CALL HANDLING

MSC

CCBS Target

C

Refer to GSM 03.79

In addition:

The information element shall be present if the call is forwarded on busy and the subscriber B can be target of CCBS requests; otherwise it shall be absent.

5.6.7 Existing parameters containing CCBS specific information

Mobile Station Classmark 2 (refer to GSM 04.08 contains information whether “Network initiated MO CM connection request” is supported or not. This information is vital for the recall mechanism.

CC capabilities (refer to GSM 04.08) contains information whether “Prolonged Clearing Procedures” are supported or not. This information is vital for the activation mechanism.

SS-Code and SS-Status (refer to GSM 09.02) contains information whether CCBS service is provisioned to the subscriber. Both originating and destination CCBS service have their own SS-Code.