Page 456 - 5G Basics - Core Network Aspects

1 Core network aspects

The PAM-SCF processes the deregistration request and updates the mobile user's terminating subscription
status in HLR/AuC (HSS) when the HLR/AuC (HSS) supports this function.

After finishing the deregistration processing, the PAM-SCF responds with the deregistration result to the AP
function via the SRF in-band. The AP function sends the deregistration response to the terminal if the terminal
is still accessible.

7.3.2.3 Originating call
Upon receiving an originating call request from a MS PAM function, the AP function sends an outgoing call
request to the CCF/SSF with the information containing the SAC of the PAM service, the request type
(originating call) and the terminal identifier (in case an analogue line is used) or the subscriber number (in
case an ISDN line is used).
The CCF/SSF uses the CLI (subscriber number) received from the user (the AP function) if it is valid; otherwise,
the CCF/SSF inserts the network provided CLI of the fixed access line to which the AP is connected, the
CCF/SSF triggers and queries the PAM-SCF for instructions.
The PAM-SCF instructs the SRF to collect the dialled number from the AP function and the AP function returns
the dialled number received from the MS PAM function to the SRF which relays the dialled number to the
PAM-SCF.

The PAM-SCF processes the originating call request accordingly and controls the modification of the CLI to
the MSISDN.
7.3.2.4 Terminating call

A terminating call to a MSISDN is routed to the "home switch" supporting the assigned PAM service number
which treats the call as an IN call and queries the PAM-SCF for instructions.

• If the user is currently registered at an AP, the PAM-SCF responds with routing instructions in the
form of a specific AP to which to route the call for completion together with the updated CLI carrying
the terminal identifier in case an analogue line is used, or in the form of a subscriber number
corresponding to the terminal to which to route the call for completion in case an ISDN line is used.
In case the call cannot be completed to the AP, the PAM-SCF provides the instructions to forward
the call to the MSISDN associated with the subscriber. In the latter case, the call must be
appropriately labelled to prevent circular routing.
• Otherwise, if the mobile user is not connected to any AP, the call is directly routed to the terminal
via the mobile network.

7.4 Allocation of functional entities to physical nodes
For each functional model given in Figures 1 and 2, two scenarios are defined as follows:
• The functional entities of IN are allocated to different physical nodes such as SSP, PAM-SCP and IP.

• The functional entities of IN are allocated to one platform referred to as PAM service platform.
In each case, the functional architecture and information flows are the same.

7.4.1 User assigned a discrete PAM service number
Figure 3 illustrates the scenario of allocating the functional entities to different physical nodes when a fixed
PAM service number is used.

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