The action of camping on provides access to services. The network provides different levels of service to a UE in either Idle mode or Connected mode. Three levels of services are defined:

LIMITED SERVICE: emergency calls on an acceptable cell.
Acceptable cell: UE may camp to obtain limited service like emergency call. The minimum set of requirements for initiating an emergency call in a UTRAN network are:

• The cell is not barred.
• The cell selection criteria are fulfilled.

NORMAL SERVICE: for public use on a suitable cell.
Suitable cell: UE may camp on to obtain normal service. Such a cell shall fulfill all the following requirements:

• The cell is part of the selected / registered / equivalent PLMN
• The cell is not barred
• The cell is not part of a forbidden registration area
• The cell selection criteria are fulfilled
• In case of a CSG cell it is part of the white list

OPERATOR SERVICE: FOR OPERATORS ONLY ON A RESERVED CELL.
Reserved cell: When the cell status “reserved for operator use” is indicated and the Access Class of the UE is 11 or 15 the UE may select/re-select this cell if in Home PLMN. Set by O&M parameter.

Barred cell:

When cell status “barred” is indicated the UE is not permitted to select/re-select this cell, not even for limited services. This information is set by office data.