Page 461 - 5G Basics - Core Network Aspects

Core network aspects 1

• When a MSISDN is used as the PAM service number:

The corresponding relationship between the user identity and the IMSI is statically created when
the user subscribes to the PAM service, while the user's MSISDN, the AP address and the terminal
identifier need to be dynamically updated when the user registers and deregisters. The user's
MSISDN needs to be retrieved from the HLR/AuC (HSS) using IMSI which is translated by the PAM-
SCF using the user identity.

Once the correlation of the mobile user with the AP address and the terminal identifier is made:
• originating calls of the mobile user through the AP function need to carry the AP address and
terminal identifier and the PAM service number associated with the AP address and the terminal
identifier is presented as CLI;
• terminating calls to the PAM service number need to be offered only to the mobile stations
associated with the AP address and the terminal identifier.
When a mobile user is connecting to an AP with ISDN line, an individual subscriber number is assigned to the
mobile station and the PAM-SCF needs to set-up mobile station-subscriber number association. Once the
mobile station-subscriber number association is made:
• all calls originated by the terminal through the AP function need to carry the subscriber number of
the terminal and the PAM service number associated with subscriber number is presented as CLI;
• terminating calls to the PAM service number shall be offered only to the mobile stations associated
with the subscriber number.

8.3 User profile treatment
When a MSISDN is used as the PAM service number, the PAM-SCF needs to have the latest service profile of
the mobile user in order to provide the set of services associated to the user when utilizing fixed access. This
can be implemented in two ways at the discretion of the PAM-SCP implementer:

• the PAM-SCF requests the service profile from the HLR/AuC (HSS) whenever the data is needed; or
• the platform acts like VLR: It stores the user profile during user registration and keeps the data
HLR/AuC (HSS) as long as the user does not change the AP he is registered at.

8.4 Emergency call handling
When an AP function detects that an emergency short number has been sent, the call will be treated as an
emergency call from the fixed access line to which the AP is connected, irrespective of successful registration
or authentication.

8.5 Video call handling
The CS video telephony service needs to be supported and requires the AP function to support the ISDN
interface. Hence, this service is not available when the AP is connected to a PSTN access line.
The video phone call of the mobile user through the ISDN access is over a 64 kbit/s/56 kbit/s transparent
data bearer.
A video call between a mobile user utilizing an ISDN access point and other terminals supporting the same
codec is handled in the same manner as a normal voice call and is transparent to the PAM-SCF and the AP.
Codec negotiation may be required and is performed in-band between the terminals.
A video phone call between a mobile user and other types of terminals supporting different codecs is possible
when such kind of interworking is supported in either the underlying fixed or the underlying mobile network;
otherwise, the video phone call may be downgraded to a voice call or the user may abandon the call.

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