An additional control bit known as "Access Class 10" is also signalled over the air interface to the UE. This indicates whether or not network access for Emergency Calls is allowed for UEs with access classes 0 to 9 or without an IMSI. For UEs with access classes 11 to 15, Emergency Calls are not allowed if both "Access class 10" and the relevant Access Class (11 to 15) are barred. Otherwise, Emergency Calls are allowed.
Multimedia Priority Service (TS 22.153
) shall be assigned its own unique access class value (i.e., one of the special access classes 11 to 15). The assigned access class value for Multimedia Priority Service is based on regional/national regulatory requirements and operator policy.
To protect the user from the effects of a misbehaving UE (e.g. causing additional charges, degraded performance) and to protect the network operator's network capacity, including radio resources and network signalling and processing, means shall be provided for the HPLMN/EHPLMN and the VPLMN to provide an indication to the UE as to which network provided services or functions it is not allowed to use.
The Selective UE Capabilities list shall be maintained in the UE and the UE shall not request any services indicated as disabled. At registration the HPLMN/EHPLMN or VPLMN may interrogate the status of the list and provide a new list.
The Selective UE Capabilities list shall not be deleted at switch off and will remain valid until a new list is provided by the network. The Selective UE Capabilities list relates to the ME and not to the subscription.
It should be ensured that UEs are not maliciously disabled, including malicious disabling by a VPLMN, or accidentally disabled, or kept disabled, and there shall be a mechanism for restoring disabled UEs in all situations (e.g. in the case that the serving network does not support the control of UE Capabilities).
The UE should use the indications given in the Selective UE Capabilities list to inform the user of the non-availability of services or functions.
There shall be a means for the network to provide an optional customer service number(s) which can be used, by the user, to assist in determining the cause of non-availability of specific services. The specifications should also provide the capability for the network to include an optional text string that will be displayed by the UE.
The UE Capabilities list shall take precedence over subscribed services.
The services to be included in the list are:
Call Control functions
Emergency Calls (including the (U)SIM-less case and subject to regional regulatory requirements, i.e. emergency calls shall not be disabled in regions where support of them is required)
SMS, via CS and PS
LCS, via CS and PS
GPRS based services