Inter Operator Roaming

[srilasitha]

Dear All,

We are testing on inter operator Roaming and come across following issue.

Other operator SIM does not automatically reselect to our network when it goes to a no coverage in its network .the phone keep in searching mode. ( we have good coverage above -80dbm)

In the drive test no location update request is sent.

If we manually select our network then the phone select to our network and location update is successful.

When I have tested in another LAC in the same MSC with phone locking to GSM1800 only, then the phone automatically selected to our network when other operator has no GSM1800 coverage.

Please advice

[freakturd06]

This maybe the reason you can not connect automatically:

1. Initially since two simcards belong to different networks, the PLMN of either networks are blacklisted to each other.
2. Although there is roaming agreement, which means, you allow other PLMN to connect to your network, the sim of other network will not automatically connect to your network because it is aware that its PLMN is blacklisted to other PLMN other than its network.
3. When you force to connect the sim manually to other PLMN, the PLMN you are trying to connect (the other operator) will check if the PLMN belongs to its blacklisted list and will not allow to connect. Otherwise if it is in its white listed PLMN which is the case of roaming, it will allow the other network sim to be connected.

[srilasitha]

Thanks for the Reply.

Is that you mean the following ? . What if the SIM is not a USIM ?
Is there any other posibilities


Forbidden PLMNs

An attempt to register to a VPLMN could be rejected due to PLMN not allowed .In this case, the related PLMN will no longer be used for automatic PLMN reselection. Indeed, the PLMN becomes a forbidden PLMN
(FPLMN) and its identity is stored in the forbidden PLMNs list used for this purpose in the USIM. A PLMN will be removed from the forbidden PLMN list in case of successful registration following its manual selection. The list of forbidden PLMNs in the USIM will not be lost when the UE is switched off or the USIM is extracted. An optional extension of this list may be stored in the terminal’s own memory.
In addition to the list of forbidden PLMNs valid for both CS and PS services, theUE handles another list named forbidden PLMNs for GPRS service which is only valid for PS services. A VPLMN is added to the list when it has been rejected due to GPRS services not allowed in this PLMN during a registration attempt. This list, which is stored in the terminal’s memory, is deleted in case of terminal switch off or removal of the USIM. A PLMN is removed from the list of forbidden PLMNs for GPRS service after a successful registration on that PLMN following its manual selection.

[freakturd06]

Yes, you can say USIM as SIM and Forbiden PLMN as Blacklisted PLMN.
You need to manually connect as stated below because from the very start, the USIM will never try to connect automatically to other PLMN because the SIM is aware that it is forbidden to connect to other PLMN.


Thanks for the Reply.

Is that you mean the following ? . What if the SIM is not a USIM ?
Is there any other posibilities


Forbidden PLMNs

An attempt to register to a VPLMN could be rejected due to PLMN not allowed .In this case, the related PLMN will no longer be used for automatic PLMN reselection. Indeed, the PLMN becomes a forbidden PLMN
(FPLMN) and its identity is stored in the forbidden PLMNs list used for this purpose in the USIM. A PLMN will be removed from the forbidden PLMN list in case of successful registration following its manual selection. The list of forbidden PLMNs in the USIM will not be lost when the UE is switched off or the USIM is extracted. An optional extension of this list may be stored in the terminal’s own memory.
In addition to the list of forbidden PLMNs valid for both CS and PS services, theUE handles another list named forbidden PLMNs for GPRS service which is only valid for PS services. A VPLMN is added to the list when it has been rejected due to GPRS services not allowed in this PLMN during a registration attempt. This list, which is stored in the terminal’s memory, is deleted in case of terminal switch off or removal of the USIM. A PLMN is removed from the list of forbidden PLMNs for GPRS service after a successful registration on that PLMN following its manual selection.

[srilasitha]

Thanks for the post. I have listed the additional information I found during my study.

1) Upon switching on, when an IMSI is available and there is no registered PLMN on the SIM, the MS shall select its Home PLMN and perform the cell selection procedure.
2) If the MS loses radio coverage for its registered PLMN, and the MS is in automatic PLMN selection mode, it shall attempt to select its Home PLMN.
3) If the Registered PLMN is unavailable due to the loss of radio coverage and the MS is in automatic PLMN selection mode and the HPLMN is also unavailable, it shall attempt to select a suitable cell and access the PLMNs in turn, in the order of priority as stored in the SIM.
4) If there is no registered PLMN in the SIM or the registered PLMN is unavailable and If the Home PLMN is unavailable and the MS is in automatic PLMN selection mode, it shall attempt to select a suitable cell and accesses the PLMNs in turn, in the order of priority as stored in the SIM, upon switching on and when the IMSI is available.
5) An MS, roaming in a VPLMN whose MCC is the same as the MCC of the IMSI, shall periodically attempt to obtain service on its Home PLMN in automatic mode. For this purpose, a value T minutes, which is the HPLMN search period, may be stored in the SIM; T is either in the range 6 minutes to 8 hours in 6 minutes step or it indicates that no periodic attempt shall be made. If no HPLMN search value is available on the SIM the mobile equipment shall use a default value of 30 minutes.
6) At switch on, the MS selects and attempts to perform a Location Update on the Registered PLMN if it exists. If the registered PLMN is a VPLMN of the SIM's home country, the MS shall wait at least 2 minutes before attempting to obtain service on its home PLMN.

[srilasitha]

Attached a good document found during national roaming testing exercise.

Please add reps