Dual Sim - Foreign network problem


For the last 2 weeks I have a serious problem with my dual sim on my FP2.
I live in a region close to 2 countries and I’m unable to keep my 2 sim cards connected to my local network company at the same time. When one is connected to it, the other always stays connected to some other foreign company.

When I try to manually select my favourite network company on this sim card slot, the network doesn’t appear in the list EVEN if my other sim card is connected to it…

I tried to reset the settings and to switch the cards in the slots but nothing…
Do you have any idea how to solve this…?
Thank you!

Which 2 countries are we talking about and which operators? Are you sure the foreign SIM’s operator has a roaming contract with your local network?


It is between Switzerland and France.
the Operators are Salt and in France it’s connecting either to Orange F or Bouygues…

Okay, so if I understand you correctly, you have two Salt SIMs?

In the Fairphone 2, only one of the SIMs at a time can use a 3G/4G network. Maybe the problem is that Salt’s 2G network does not reach you?


Yes exactly.
I set up one card with 4g, the other one with 2g, but even like this, one is not finding the Salt network (even for calls/SMS) and keeps connecting to some foreign operator… I tried inverting the sd cards in the slots and there is always one not finding the Salt network. Also tried to put the cards in other Smartphones and they’re working fine. So it looks like it is more of a problem of the Software…

What is not clear from your post is whether this is related to the 2G or 4G network.

To which network mode (2G or 2G/3G/4G) is the SIM set which receives no Salt network, and does this carry over when you change which SIM uses 4G?


Have you also tried to individually test each SIM card as single in each slot?

Can you get each card registered to a network using only single-SIM mode?

If not, how are the results after testing? What’s working in single-SIM mode?

Could this problem has anything to do with the fact that only one sim can be set to 3/4G?
One sim to 3/4G then the other gets 2G.

Sure, this also has to be considered.

Each time @Martin1234 switches locations he has to re-configure this setting according to which network provider to use for data [3G/4G] and which for phoning [2G only] or if he’s living close to borders he should choose a combination which works best for his situation so the phone not necessarily have to permanently search for a network with better connectivity.
But if reception of both SIM cards is not so good then it’s tricky to be done.

By the way: is it a problem if your phone is connected abroad? Do Swiss people (non-EU) have to pay for roaming inside the EU?

Thank you for your answers!
The thing is that I set one card to 3/4G and the other to 2G but even like this, one is not finding the correct operator when the other is…
I tested both cards as Single Sim, and they work perfectly. It’s only when they’re both used that one is not working (and not always the same one, what makes me think that the problem comes from the OS itself. I also changed both cards, they’re brand new.)
This problem appeared 2 weeks ago and everything was working fine before

Do you think formatting and resetting the FP2 is the only and last option or does someone has another idea? :wink:

PS: Yes swiss mobile operators are super expensive and are not covering any EU country so the roaming taxes are extremely expensive…

Which one is not finding the network? The one on 3/4G or the one on 2G?

Are you on the latest Android 7? Have you received any OS security updates lately?

According to the bugtracker there are users having troubles with two SIM cards in use. But as you wrote it just has started about two weeks ago, before everything was fine there may be a different cause.

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