4.2.16 EF_FPLMN (Forbidden PLMNs)

31.1023GPPCharacteristics of the Universal Subscriber Identity Module (USIM) applicationRelease 17TS

This EF contains the coding for n Forbidden PLMNs (FPLMN). It is read by the ME as part of the USIM initialization procedure and indicates PLMNs which the UE shall not automatically attempt to access.

A PLMN is written to the EF if a network rejects a Location Update with the cause "PLMN not allowed". The ME shall manage the list as follows.

When n FPLMNs are held in the EF, and rejection of a further PLMN is received by the ME from the network, the ME shall modify the EF using the UPDATE command. This new PLMN shall be stored in the n^th position, and the existing list "shifted" causing the previous contents of the first position to be lost.

When less than n FPLMNs exist in the EF, storage of an additional FPLMN shall not cause any existing FPLMN to be lost.

Dependent upon procedures used to manage storage and deletion of FPLMNs in the EF, it is possible, when less than n FPLMNs exist in the EF, for ‘FFFFFF’ to occur in any position. The ME shall analyse all the EF for FPLMNs in any position, and not regard ‘FFFFFF’ as a termination of valid data.

Identifier: ‘6F7B’		Structure: transparent			Mandatory
SFI: ‘0D’
File size: 3n bytes, (n≥ 4)			Update activity: low
Access Conditions: READ PIN UPDATE PIN DEACTIVATE ADM ACTIVATE ADM
Bytes	Description			M/O		Length
1 to 3	PLMN 1			M		3 bytes
4 to 6	PLMN 2			M		3 bytes
7 to 9	PLMN 3			M		3 bytes
10 to 12	PLMN 4			M		3 bytes
:	:			:		:
(3n-2) to 3n	PLMN n			O		3 bytes

‑ PLMN

Contents:

Mobile Country Code (MCC) followed by the Mobile Network Code (MNC).

Coding:

according to TS 24.008 [9].

For instance, using 246 for the MCC and 81 for the MNC and if this is stored in PLMN 3 the contents is as follows:

Bytes 7 to 9: ’42’ ‘F6′ ’18’.

If storage for fewer than n PLMNs is required, the unused bytes shall be set to ‘FF’.