Physically add second sim

I use several eSIMs and a physical one. Being able to just switch numbers without having to shut down the phone or carrying those around is a feature I wouldn’t give up again, now that I have it.

I wouldn’t have bought the FP4 if they hadn’t included it, eSIM support is future proofing and I’ve had to stop using my (still working) previous phone because of something similar.

Even if you don’t like it, you might need it in 5 years.


Hm… Maybe it’s like with USB-C in that the technology itself is cool, but the adaptation is so subpar that it cannot live to its potential

You scan a QR-code and moments later you’ve got a new SIM in your phone, I find that very convenient.
I can get a new SIM / number in like 5 minutes as well, that’s very useful from a privacy / phone spam perspective.

Try it at some point, it’s actually quite handy :slightly_smiling_face:


That sounds really useful and is a good reason to have it, but I still want to try this and give the option to anyone who wants to have 2 physical sim.

It’s also a cool project that is fun to figure out and givens us a better understanding of how the phone works. Which can help people in the future repair them.

I’ve already ordered all the pieces and I’m just waiting for them to start. I’ll keep all of you updated on what happens


Oh, by no means did I mean you shouldn’t carry on with this project.

I’m closely following every update, very exciting where this might go and so much learning opportunity for people who don’t know a lot about electrical engineering, like me :smiley:


Strange statement. Therefore I may assume you have not yet seen many electronic devices from the inside.
This is common practice.

Take a look at more electronic circuit boards and you will realize there are many more positions free where parts could have been placed but actually aren’t.
It’s not because someone forgot to place them but for intentional reasons.

  1. Sometimes there may be different device variants for which the manufacturer don’t want to design several pcb layouts but change functionality by different part placements.
  2. It could also be to react to changing, maybe unforeseen conditions, while the device is being designed/manufactured. Re-configuring pick and place robots is much faster, easier and cheaper than re-designing the entire pcb layout and maybe having to get it re-certified and tested according to ems and other requirements.
    There are many scenarios possible. With this hybrid option there is also flexibility. Usually there’s at least one sim card/number registered to the device. (who/how many users keep a mobile with no sim at all just using wifi…)

As we had it with FP2 already, how come the 801 SoC capabilities weren’t fully utilized to its maximum extend (e.g. up to 21MP camera, VoLTE, HD calling over 3G…, NFC, display resolution up to 2Kx2K, USB3.0…)? [Snapdragon 801 Processor | Qualcomm]
Users were already complaining about its high price, to me this seems to be the most important reason.

For the FP4 it may could have been a version aspect for me too like the cheaper option with 6GB/128GB dual sim socket, not so capable camera etc. and the largest, more advanced 8GB/256GB version with eSim/sim socket, 48MP camera etc.
I didn’t dig into how many features of the FP4 SoC aren’t utilized, but using them all surely would had increased the price noticeably.
Who knows for sure about the reasons if not the manufacturer.

So the fact such pins are available on the pcb but unused is not new to me at all after having seen so many devices of different type from the inside. Nothing I actually bother about anymore.


Just got all the parts, any last words of advice? If not i will let you know what happens.

I will try at first to just solder the parts and if it doesn’t work I’m going to desolder the esims chip


Ok, so i was able to solder the sim slot with enough persistence, but I can’t solder on the other small component. I need to reflow the components on but I have never done it, I don’t have the components and don’t know where I could find the equipment. So I might have to wait a bit to finish this project.
If anybody knows where i could borrow/use that equipment in Montreal, Canada it would be really helpful

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Don’t know if this is the right point in time to get started with this but at least I have seen people using equipment like this to do the job… Other people just use their baking oven as explained here:

It is not uncommon that PCBs have left some roots of states of the development process. As you know I work for an electronics company and we have many products where you can find wireings that never were/will be used.
The reason is just simple. The remove just takes time for changing drawings, new prototypes, additional testing and of course the potential of doing mistakes in the change process. So it is easier to just not placing some parts on the PCB.
Maybe the E-Sim feature was not planed from beginning of the development.

I do use an E-Sim from WeTell and it works pretty well. The potetial of having a physical Sim slot available for a foreign Sim is still a benefit.

Edit: Didn’t read the whole thread by typing this answer. @Patrick1 pointed it out already.


Yo may try to solder it with a hot air gun on 300°C and low airflow.


tried that but I don’t have one with low enough airflow to make it work, but I’m doing research to learn how to do it with an small oven. thanks Martin_Anderseck


If you plan to make yourself a present, I can recommend JBC soldering equipment.


So JBC really seem to be very good gear of top quality… I’m having an eye on some…but haven’t had enough time to get deeper into it for finding my preferred model. So the price seems justified.
Anyway, thanks for the hint.

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Having eSIM available is even more useful since there are apps to get prepaid eSIM in foreign countries if you are traveling.


The german wikipedia article about reflow soldering has details about different reflow soldering processes.

A translation is available using google: Reflow-Löten – Wikipedia


can you recomment an app?

Airalo is one of the most popular ones. Also see this review by Michael Vance, he compared multiple solutions: All International Travel eSIM Apps Reviewed! - YouTube

We have a bit of information as well in the forum wiki for the FP4

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