Each GGSN can connect to multiple external networks and includes a logical element, known as an APN element, 

to perform the duties of communicating with each specific external network. 😶‍🌫️

The name assigned to an APN usually reflects the network or service to which it connects, so typical APNs are 'Internet', 'MMS' and 'ims'. The SGSN and GGSN generate CDRs for each data session and transmit them to the network.

The 4G PS core network uses devices similar to the SGSN/GGSN, which are called S-GW and P-GW . Connection control and subscriber management in 4G networks is done with MME . Billing data for 4G data sessions are generated in S-GW and P-GW.

5G networks use similar mobile data processing methods as 4G networks, although the names of network nodes have changed again:
instead of packet data processing node types, the 5G network has only one type of device known as UPF . Connections and subscribers are managed by a node known as AMF (Access and Mobility Management Function). Billing data is generated in the UPF.

Voice and text events usually have a very clear temporal identity, in the sense that there is from the start time to the end time of the voice call and the transmission time or
delivery time of the text event. The call records for SMS events identify the cell ID that was used to transmit the text message.
SMS transmission usually takes only a few tens of milliseconds, there is no mechanism to allow switching during an SMS event, so SMS records usually only specify the identifier of the "start" cell.

In the case of both voice and SMS events, cell site analysts can be absolutely certain that the target phone was within coverage of the listed cells at the time the event began and (in the case of voice records) at the time the event began and at the time it ended. 👌

Thus, from the cell site reports, it can be concluded with respect to the cell serving the important location that the use of that cell is consistent with the possibility that the target phone may have been "in" that location GPRS/PS data CDRs may be much less certain about the correlation of their timestamps and starting cells, and therefore potentially less valuable in terms of the evidence about the cell site that they can provide.
A new GPRS/PS data CDR opens when the mobile device establishes a new logical session with the data network Internet📡 for example, there each new session is assigned a separate identifier.

Separate CDRs are generated by the SGSN/S-GW and GGSN/P-GW nodes.
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