Page 448 - 5G Basics - Core Network Aspects

1 Core network aspects

Once the user is authenticated and registered, he is provided voice and video communication using the
PSTN/ISDN via the fixed network access point at which he is registered consistent with the limitations related
to the capabilities of the access point and the terminal device being used.
The mobile user deregisters when he leaves the access point.

6.4 Call handling

The service supports two different treatments for incoming and outgoing calls according to the service
number used.

6.4.1 User assigned a discrete PAM service number

When using a fixed PAM service number separately assigned from the MSISDN, the handling of the call is as
follows:
• Originating call

If the user is currently registered at an AP, the originating call will be handled through the PSTN/ISDN
when the fixed network access is available. The fixed PAM service number is presented as the calling
party number to the called party, and the call is treated according to the service subscription
associated with the fixed PAM service number. The call is charged against the fixed PAM service
number. If the fixed network access is not available (i.e., the AP that the user is registered at
encounters an all fixed access circuits busy situation), the call will be handled through the mobile
network, if available, as a normal mobile originating call. The MSISDN is displayed as the calling party
number and the call is treated according to the service subscription associated with the MSISDN in
the mobile network. The call is charged against the MSISDN.
If the user is currently not registered for fixed network access, the originating call will be handled
through the mobile network, if available, as a normal mobile originating call. The MSISDN is
displayed as the calling party number and the call is treated according to the service subscription
associated with the MSISDN in the mobile network. The call is charged against the MSISDN.
The user is provided with visibility of the selection of the radio access (PAM AP or mobile network)
used for the originating call.
• Terminating call
When a call is placed to a fixed PAM service number, there will first be a check for whether the PAM
user is registered at an AP. If so, the call will be delivered via the PSTN/ISDN to the AP at which the
PAM user is currently registered, and the call is treated according to the service subscription
associated with the fixed PAM service number. If call completion through the PSTN/ISDN fails (e.g.,
all the access circuits to the AP are busy), the call will be forwarded to the mobile network using the
MSISDN and the call is treated according to the service subscription associated with the MSISDN.
If the user is currently not registered at an AP, a call to a fixed PAM service number will be forwarded
to the mobile network using the MSISDN as the forwarded-to number and the call is treated
according to the service subscription associated with the MSISDN.
Charging to the originating party will not be affected when a call is forwarded from the PSTN to the
MSISDN of the terminating party.
A call to the MSISDN associated with the PAM user is delivered to the mobile network as a normal
mobile terminating call.

6.4.2 MSISDN as the PAM service number
When using the MSISDN as the PAM service number, the handling of the call is as follows:
• Originating call

If the user is currently registered at an AP, an originating call will be handled through the PSTN/ISDN
when the fixed network access is available. If the fixed network access is not available (i.e., the AP
the user is registered with is busy), the call will be handled through the mobile network, if available,
as a normal mobile originating call. Whether the call is handled through the legacy PSTN/ISDN, or

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