ubuntu-phone team mailing list archive

[sturmflut <sturmflut@xxxxxxxxxxxxxx>]

Dear list,

I'm the original reporter of bug 1449990. Today I took the time to read
the technical stuff (3GPP standards) to find out how National Roaming is
supposed to be implemented, and then I tried to find out what the
operators are actually doing and why it just works on Android.

Hope this helps:

Assuming a 3GPP-compliant handset (any smartphone should do) and
assuming the operators don't want to hand out new SIM cards to
everybody, the way to go is to use the "Equivalent PLMN" (EPLMN) list
stored on the SIM card. All mobile networks on this list have to be
considered equal by the device, so if I put my home network "E-Plus" and
the "other" network ("O2") on it, the phone has to treat O2 like my home
network.

The trick is that this list can be automatically updated over the
network by the home operator, so the process is seamless to the
subscriber and requires at most a device reboot.

http://mobilesociety.typepad.com/mobile_life/2015/06/equivalent-plmns-in-germany-telefonica-o2-and-eplus-network-network-integration.html
documents that my operators are using this feature.

So I think the question is: Do our Ubuntu phones maybe not honor the
EPLMN? Is there a way to debug this any further, maybe dump the
currently used SIM parameters?

cheers,
Simon

Am 12/09/2015 um 11:37 AM schrieb Jacob Nielsen:
> I have an MX 4, currently on rc-proposed. Bug #1449990, or something
> very similar, affects me as well.
> 
> Output from list-operators:
> [ /ril_0 ]
>     [ /ril_0/operator/23802 ]
>         MobileCountryCode = 238
>         MobileNetworkCode = 02
>         Name = Telenor DK
>         Status = available
>         Technologies = umts
> 
>     [ /ril_0/operator/23866 ]
>         MobileCountryCode = 238
>         MobileNetworkCode = 66
>         Name = Telenor DK
>         Status = current
>         Technologies = gsm umts
>     [3 entries removed]
> 
> MCC 238 is Denmark. MNC 02 is Telenor, MNC 66 is the united networks of
> Telenor and Telia (tt-network.dk). My carrier is an 'MVNO', OK Mobil,
> who's using Telenor's network. Unlike the bug above, in this case the
> network name is the same for the two entries. (The 02 network sometimes
> shows up as just "Telenor" for some reason. I can still connect, and
> then the name will change to "Telenor DK" in the carrier list.)
> 
> The networks should be considered equal by the phone. But when set to
> select a carrier automatically the phone will always choose the "66"
> network and then insist it's roaming - which means no data connection,
> as data roaming is switched off. Through the carrier list I can manually
> connect to the other network and get data - but the phone will always
> eventually reconnect to the "66" network on its own, even if left
> stationary.
> 
> (There seems to be no noticeable difference in signal strength between
> the two networks here. Why will the phone prefer roaming to a network
> that can't provide data, when the network matching the SIM is available
> and not significantly weaker?)
> 
> From comment 6 on bug #1449990: "When you are registered in a network
> with different MCC/MNC codes to the ones in your SIM, you are roaming
> unless the MCC/MNC of the network you are registered to is in a list
> that is stored in a file on the SIM." Makes sense - yet my old SIM,
> which pre-dated the Telenor/Telia cooperation, worked as expected in my
> Android phone when using the same settings (data on, data roaming off):
> There'd be two 3G "Telenor DK" entries in Android's carrier list, one of
> which had a home icon. I could select either and get a working data
> connection.
> 
> When I contacted OK Mobil about this they provided me with a new SIM
> card (for free - as an exception). Unfortunately the phone's behaviour
> is the same with the new SIM.
> 
> Can I do anything to help fix this? I'd lobby for that bug to be moved
> up from 'wishlist' status, as this issue means that for the time being
> I'll have to stick to Android for my daily device.
> 
> Regards,
> Jacob Nielsen
> 
>