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Reply To: Country Border Roaming Issue


Pan, you said

“To ParaHO:
In GSM SIM the VPLMN is added in Forbidden PLMN List only if “Plmn not allowed” message is recieved by an MS in responce to on Loc_Upd request from a VPLMN. No another way to doing this. Perhaps there is capability to update this list by HPLMN operator via OTA in UMTS SIM.”

You make go point Pan. However, I not think it follows that in SIM EF PLMNsel that all roaming networks will be listed there also. So when MS attempts to Loc_Upd request to VPLMN – no roaming agreement for MCC/MNC, barred message is sent and VPLMN MCC/MNC is updated to the FPLMN.

You make good point about which OTA and USIM and I agree with you. The old GSM SIMs used type of silicon that only allow for Masked ROM and OTA was directed toward SMS using GSM SIM specific alphabet. So direct updating of EF PLMNsel didn’t happen as far as I know. USIMs use latest silicon and use flash technology allowing for instance OTA updates to many memory areas in (a) USIM module or (b) GSM module.