FP2: How to use the Dual SIM feature?


Like many others I am waiting for my FP2. This will be my first Dual SIM phone ever, and I’m trying to get my head around how to use this feature.

How will apps that link to the mobile number (e.g. WhatsApp - even if I never will use it again :wink: , or Signal) behave with two SIMs?

Can I use one SIM as my business phone number and the second SIM as a private number, data plan on the second SIM only?

Can I link the SIM to be used for outgoing calls to contacts, I.e. specifying per contact a default outgoing number?

How does Signal as a SMS/MMS replacement app behave with incoming SMS when using two SIMs?

Any apps one should look at? Anything else one should consider?

Thank you very much for your insights into this… :slight_smile:


There’s a video for the Fairphone 1 that explains parts of how dual SIM works on android. If I’m not mistaken, the Fairphone 2 will offer the same functionality, though menus will be different and it will offer profile management - a brief note can be found in the user manual on page 18/19 (note that all the pages are on a single sheet in the pdf).

Update: There is now a blog post about this on the Fairphone blog:

I have no experience with Signal, but I know that you can use WhatsApp without issues for one of the numbers - unfortunately I’m not aware of a possibility of managing two phone numbers at the same time in a single install of WhatsApp.

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Yes. The setting is in the data usage monitor and in the SIM card settings. Well, you have to set SIM1 to 2G only and SIM2 to 4G to have fast data speed. It’s in the settings at “More…” - “mobile networks”.


You can choose which SIM has the 3 or 4G connection. So your data plan can also be on the first SIM and your second SIM will have 2G.

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I have a little problem with my FP2 and the Dual-SIM. I set SIM 2 for my data, because I have my data plan on this SIM card. If I disable SIM 2, because I don’t want to be available for callers the connection for data changes automatically to SIM 1. But I don’t have any data plan on SIM 1. Also my preferred settings for outgoing text messages and phone calls change to SIM 1, also.
If I enable SIM 2 again, the data connection stays on SIM 1 and I have to manually re-set it.
I think this is a problem for all those who have a data plan on one SIM and none on the other. Does anybody has a solution for it except leaving the SIM 2 card always enabled? I would have excpected, that the settings stay what I set and don’t change without asking beforehand.

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I can reproduce that the setting of the data SIM changes when disabling SIM2. But I have disabled the data usage also in the data usage monitor (German menu: “Datenverbrauch”) and data usage on SIM1 stay disabled there when disabling SIM2. I have not tested if there is really no data flow.

So you have to set four preferences if you want to use only one SIM for data:

  1. In the data usage monitor, disable data usage for the “wrong” SIM.
  2. In the SIM card settings, set data usage to the “right” SIM.
  3. Go to “More…” - “mobile networks” and set the “wrong” SIM to 2G only.
  4. Go to “More…” - “mobile networks” and set the “right” SIM to 4G.

I have exactly these settings. But the problem stays: If I disable a SIM 2, it changes to SIM 1 for data, calls and text automatically.

Look at the data usage monitor. Is there SIM1 still disabled?

Yes it is. But if I activate the data connections in general, the SIM 1 will be used. The settings shouldn’t change at all. Even if I think of reactivating SIM 2 before activating data connections, all the time I have to set these settings again. I think it is more practical if the settings doesn’t change just because one SIM is inactive.

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I don’t have my FP2 just yet, but I’m in the process of switching providers and was also considering a second, data-only SIM. Now after what I’ve been reading here and there on the forum I’m no longer sure if this is really worth the hassles.

So I understand that you can’t simply toggle mobile data on and off on either card, is that correct? I guess I’m so used to Power Toggles I’ve come to believe this is a standard Android feature–for a single SIM, anyway. So unless I want to drill through all the layers of the settings all the time, I’d basically have to perma-enable mobile data on one of the SIMs?

What happens when you turn on Wi-Fi at the same time? How does Android negotiate which data connection has priority? Pardon my ignorance. This seems like a pretty obvious question, but I never had to ask it because I never seem to have a data plan and working Wi-Fi at the same time to begin with. That will be an all new experience for me once I’ve successfully moved to another provider.

If you have Wi-Fi and a data plan enable at the same time, the Fairphone will use the Wi-Fi.

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If you only want to use data with one SIM, you can easily toggle it on and off via the notification bar. With Android 4 this was faster and easier, but it is still easy and fast.
You’ll only have to “drill through all the layers of the settings all the time” if you often have to switch your data SIM, for example, because you’re living in one country and working in another.


As Irina_Spitznagel said you can activated or deactivated the mobile data of the currently chosen data-sim quickly via the notification bar.

but what did work better on my ZTE-Blade-C jellybean dualsimphone was switching the data-sim via notification bar (which should be added via shortcut in notification bar or shortcut) and remembering settings like which simcard should be data-sim after reenabeling it or changing phsical simcards 3rd or 4th sim in pocket

I had another problem how to use two SIM cards, one for calls and SMS, the other for Internet. I chose the settings like Tofra wrote, but everytime I wanted to call somebody, the data-card was chosen for calls.

Now I found the same feature to chose the card for making calls in my telefone-App.In the upper field (Name/Number/search) there is a field one the right side which offers aigain “settings”, and there you can chose again “call settings” and afterwards “other Phone account settings”. Now you see "Make calls with"and you can make the same choice which you can make in the SIMcard-settings under "preferred SIM for (Card1, Card2 or ask first).

That now solved my problem


So that means, if I am in a 4G-only area with no 2G coverage, I have only one working SIM.

4G is backwards designed to be able to give 2G and 3G as well.
So if one SIM is having 2G and the other 3 or 4G, both SIMs will work.

But what if there’s no 2G network within reach? What if one day the companies decide to switch of their 2G networks?

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If there is 4G, then there is also 2G.
To answer your second question with another question: What if the provides switch off 3 and 4G as well?

Is this a technical condition in the 4G standards? Can with any 2G only device connect to any 4G network?

Then there’s no network left. So yes, when the 4G networks are switched off because all the frequency bands are needed for 5G, 6G, 7G, will I still be able to use my FP2 or my old 2G-only Nokia?

Well as I said 4G is backward compatible with 2G.
Yes there are countries closing down there 2G or have just one provider still providing 2G. Reading this wiki about 2G will tell you more about it.
In the Netherlands 4G isn’t available everywhere. It will take years before 5G is available in the Netherlands.
So let say that in 5 years time 2G will be switched off. Do you think your mobile will last another 5 years.
I don’t think so. By then you will have a new mobile. You still can call with a mobile which can do 4G. It’s up to you if you want to use it to the full benefit using internet on your mobile.