03.603GPPGeneral Packet Radio Service (GPRS)Release 1998Service descriptionStage 2TS
The SGSN knows from the subscription data the parameters (S for Subscribed): PDP type (S), PDP address (S), APN (S), and VPLMN address allowed.
The SGSN may know from configuration the default APN supporting a given PDP type. This APN is called APN (SGSN) and does not include an APN Operator Identifier.
The SGSN knows the parameters requested by the MS (R for Requested): PDP type (R), PDP address (R), and APN (R). APN (R) is the APN Network Identifier requested by the MS.
In case of "an APN chosen by the SGSN" the activated PDP context is always linked with a dynamic PDP address.
An MS may have multiple subscription records for the same PDP type and the same PDP address, but with different APNs.
An MS may have one or two subscription records with the same PDP type and the same APN: one with a static PDP address, one with a dynamic PDP address.
When the MS is in its HPLMN, if the MS requests an APN that does not correspond to any GGSN of its HPLMN, the request shall be rejected by SGSN. When the MS is in a VPLMN, if the MS requests an APN that does not correspond to any GGSN of its HPLMN nor of this VPLMN, the request shall be rejected by SGSN.
If APN (S) = wild card (see GSM 03.03), it means either:
– that a default APN (a default PDN) has to be chosen by the SGSN (APN (SGSN)) if no APN (R) has been provided; or
– that a PDP context with dynamic PDP address may be activated towards any APN requested by the MS.
In order to derive APN (R) from the APN sent by the MS, the SGSN shall check if the APN sent by the user ends with ".gprs". If not, then APN (R) is equal to APN sent by the MS. If yes, then APN (R) is the APN sent by the MS without the three last labels. If yes, then the APN-OI shall be saved for later use, see Figure A.4.