Page 453 - 5G Basics - Core Network Aspects

Core network aspects 1

7.2.4 PAM-SCF

The PAM-SCF provides the following functions:
• Authentication function to perform authentication when a mobile user requests fixed network
access via an AP. An SRF may be needed to collect identification and authentication parameters. For
both numbering types, the PAM-SCF provides the same network security mechanism as used in the
mobile network corresponding to another (mobile radio access) mode of the terminal.
– When a fixed PAM service number is used, the PAM-SCF generates the authentication data on-
demand as done in HLR/AuC (HSS).
– When a MSISDN is used as the PAM service number, the PAM-SCF requests the authentication
data from the HLR/AuC (HSS).
• Mobility management to handle the user moving between different APs or moving into or out of
range of an AP. This is managed via registration and deregistration procedure. When the PAM-SCF
receives the registration or deregistration requests from an AP function, the PAM-SCF updates the
service information as follows:
– In case a fixed PAM service number is used, the PAM-SCF updates the PAM user's registration
status and the information relevant to the user's fixed network access point in the database.
– In case a MSISDN is used as the PAM service number, the PAM-SCF updates the PAM user's
registration status and the information relevant to the user's fixed network access point in the
database and updates the mobile user's PAM service subscription status in HLR/AuC (HSS) when
the HLR/AuC (HSS) supports this function.
• Call control function:
– When the PAM-SCF processes an originating call request, it modifies the CLI to the fixed PAM
service number (when a separate PAM service number is used) or the MSISDN (when MSISDN
is used as PAM service number) of the PAM user.
– When the PAM-SCF processes a terminating call for a PAM user, in case the user is currently
registered at an AP, the PAM-SCF instructs the SSF to complete the call via PSTN/ISDN. In case
a PSTN line is used, the PAM-SCF instructs the SSF to route the call to the specific AP at which
the user is registered with the updated CLI carrying the terminal identifier. In case ISDN line is
used, the PAM-SCF instructs the SSF to route the call to the specific subscriber number
corresponding to the terminal. If the call cannot be completed to the AP function, the PAM-SCF
provides instructions to forward the call to the MSISDN of the PAM user. In the latter case,
when MSISDN is used as the PAM service number, 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.
• Service treatment function: the PAM-SCF provides the services according to the service profile
associated with the service number. The service profile associated with the fixed PAM service
number is statically stored in the PAM-SCF. The service profile associated with the MSISDN is
downloaded from the HLR/AuC (HSS) after registration and deleted after deregistration.

7.2.5 SRF
The SRF functional entity provides the AP function in-band DTMF/FSK interaction via the SSF/CCF for the
purpose of obtaining user identification and authentication parameters. The SRF accepts instructions from
the PAM-SCF concerning the user interaction to be conducted and the parameters to be collected and
returned to the PAM-SCF. The SRF is connected to and is disconnected from the AP function by the SSF/CCF
as directed by the PAM-SCF.

An example of an implementation of the PAM service using the MSISDN as the PAM service number is
provided in clause 9.

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