What happens when UE switched on in a cell where his operator network does not exist?

[nemjain]

I have a question regareing UMTS camp on producedure.
suppose my UE is a subscriber of operator A. I put it off.
and I moved to some area where Operator A does not provide network service.
I that case how my UE will get camp on.

[Femto_Engineer]

Well in a UMTS network when a UE is switched on it starts searching through all the carrier frequencies for other PLMN if the Home PLMN is not available.

Selection of a PLMN can be 'Manual' or 'Automatic'.

Manual PLMN selection mode: The UE provides a list of other PLMN to the user and ranks them based on quality, in descending order (e.g. depending on the RSCP values).
Automatic PLMN selection mode: The UE selects a PLMN in the following order:
1. Camp onto a Home PLMN if it was available during initial PLMN selection procedure, if not
2. Camp onto the user defined secondary PLMN list (if user has defined them, SIM feature)
3. Camp onto an operator defined list (operator defines a list of alternative PLMNs if HOME PLMN is not available, might be integrated into the SIM)
4. Select the best available PLMN depending on the quality of received signal.

Successful connection onto the other PLMN depends whether the subscriber's operator has any roaming agreement with other PLMN operators.

If no other UMTS network is available, the UE might try to select other networks with different RAT access technology e.g. GSM. (also depends whether there is a roaming agreement in place with other operators). If no such agreement exist, the UE will be denied admission to the network it is trying to establish a connection with.

[firstmaxim]

PLMN selection could be manual or automatic:
In manual, the user will select the PLMN among the available PLMNs.
In automatic, the UE will use the following priority:
1.last registered PLMN
2.home PLMN (if not same as1)
3. preferred PLMN (in priority order as stored in SIM)
4.other PLMNs (based on the signal quality)
The selected PLMNs should not be in the list of the forbidden PLMN list.