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Help UMIDIGI S5 Pro: SIM not detected outside home base


May 19, 2021

I'm completely out of ideas how to fix this problem. I've searched all over the internet, but can't fix it. I've contacted the mobile carrier, they don't know. The phone manufacturer is poor with communication.

My Location: Melbourne, Australia
Phone: Umidigi S5 Pro
Operating System: Android 10
Mobile Phone Carrier: Amaysim (Optus Network)

Phone works perfectly in my home. I can make & receive calls, watch videos, download games. Everything is perfect. So, at least I know the phone can work & perform all the functions.

But, when I go outside my home base, the signal drops out completely "NO SIM DETECTED". I cannot even make & receive calls. This happens all the time. Eventually, maybe after 10 minutes (making no changes to the settings), the SIM is finally detected. But, it might easily drop out. It's totally unreliable.

To see if the problem is just poor network connection, I put the same SIM Card into two other phones (Oppo AX5 and Samsung J5108) in the same outdoor locations. Both phones easily connect to the mobile network immediately. I can make/receive calls, watch videos, connect to internet, etc. No drop outs. 100% reliability.

So, to summarise:

1) SIM card works in the Umidigi Phone at home without problems. 100% reliability.
2) SIM card does not work reliably in the Umidigi Phone outside the home base.
3) SIM card works in the Oppo phone & Samsung phone outside home base. 100% reliability.

So, it seems, the Umidigi Phone is having trouble connecting to the Mobile Network .. BUT ONLY outside my home base.

Is there some setting that needs to be adjusted? Maybe, someone has experienced the same issues with their phones or can someone with tech experience please provide possible settings that need to be adjusted?

The phone obviously can connect to the network perfectly at home. What could be causing it to not connect outside the home?

Thank you.
I can't think of any reason why location should affect SIM detection. Of course I don't know your service provider (I'm on the opposite side of the planet), so don't know whether they have any special features that might relate to a "home" basestation (those things were popular in the early days of mobile service, I've not heard of them recently), but even then I don't see how that would relate to "SIM not detected", which usually implies a fault in the SIM card (or, less likely, the phone).

You are certain that you don't have something like WiFi calling enabled, so it will work at home even if the SIM isn't functioning?

How quickly does the fault develop? Does it start when you are a hundred meters or so from the house (in which case it might be related to WiFi), or further (in which case it might correlate with a change of cell)?

I'm not aware of any obscure setting that could lock a phone to a particular cell (you'd obviously never put such a thing where civilians could find it!), and even if there were it would be weird for it to manifest as a SIM detection fault.

So, I can only guess, and the symptoms don't make much sense to me (I can see why the carrier wouldn't know what to do with this). My first thought it so ask for a replacement SIM anyway, one the grounds that "SIM not found" suggests a SIM error, even if the geographical correlation doesn't make much sense. I know you've tested it in other phones, but developing SIM faults can manifest differently in different phones (the last time I suffered one it occurred intermittently in my phone, but my wife's phone would not detect the SIM at all) so it might just be that your phone is more sensitive to it. There is of course the standard "we don't know what this is so let's see whether a factory reset fixes it" approach, but I find backing up and restoring a pain so don't like to suggest that one where I think it's unlikely to work.

One random thought: have you tried turning off location services completely? If the problem is linked to a particular cell or being connected to your WiFi then this won't matter, but if this does make a difference it would tell us that the location was a factor (and that this was a software or settings issue of some sort).
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Hi Hadron

Thank you very much for taking the time to reply & offer some really constructive input.

To answer some of the points you've raised:

1) I turned off the WiFi in my home & only used the phone via the mobile data provider. And, it works perfectly. Calls can be made/received, connect to internet, play videos. I even unplugged the internet modem into the house to make sure I was only using he Mobile Connection.

2) I actually decided to drive out last Sunday to specifically check the distances from the home.

2 kms from home = no problems, still had SIM use for phone calls & played videos

4 kms from home = problems occur; inside shops or outside on the street. At this location, I swapped the SIM I was using in my phone into the other two phones & no problems at all with those phones connecting with my SIM Card. I also swapped the SIM cards that were in those other 2 phones into my phone & the connection was lost when either SIM was in my phone.

Incidentally, all 3 SIM cards were with the same mobile carrier.
So, all 3 SIM cards did not work in my (Umidigi Phone) but worked perfectly in the Oppo & Samsung phones.

The mobile carrier actually gave me a new SIM replacement when I rang them (about the 3rd time I'd rung with this complaint). And the new SIM is what I used for all these experiments last Sunday.

3) One thing I've noticed with my phone in these locations was a small wheel keeps spinning in the top left corner with a message "searching for connection". Then the icons show it is connected to the SIM & carrier, but within seconds it drops out again. On some occasions it will eventually connect & remain connected. But, it's a complete lottery to know how long it will take to connect or how long it will stay connected.

It's sounded to me (totally a non-tech person so I'm just guessing) that the phone was constantly searching for a cell tower to connect to.

I did turn off all the "location services" since one of the website videos on this subject suggested that might help, but it didn't help.

What baffles me is why it connects perfectly inside my home. Is that just pure luck? I mean, my home could be located in any of the spots where I can't connect, so is the fact it works in my home just coincidence?

Regardless, because it works perfectly in my home at least I know the phone is able to work in Australia & I'm just wondering if there is some setting that's causing it to get "confused" when it has multiple cell towers to find?

Again, thanks for your help, so far.
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Hmm, so it's definitely not the individual SIM, and it really does depend on being in or out of a particular region, possibly a particular cell, rather than some confounding factor like WiFi range.

If it weren't for the location dependence I'd suspect a simple handset fault, but it honestly sounds like it must be a software thing (except it's not a hard cut-off, it does sometimes connect when away from home). I can't see anything in my phone's settings that could do this, and I've been through the developer options, which are hidden by default, and the hidden "Testing" menu that can be accessed by typing *#*#4636#*#* into the dialer on most phones (but if you are tempted to look at that be very careful not to change anything in there - there are things in there that can cause problems if changed, which is why it is hidden).

A real long shot: what is your preferred network mode? If it was set in an odd state like "LTE only" and there was very little 4G coverage around it could do something like this (though "no SIM detected" would still be odd), but that sounds very implausible (and I think the only way you can get into LTE-only rather than LTE-preferred on most phones would be via the hidden Testing menu, so it's unlikely you'd be in that state). I did wonder whether it might be one of these things where an unusual Chinese phone doesn't match well with the bands your carrier uses, but from a bit of web research it looks like it should support all of the bands that Optus use, so I don't think that's the answer.
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Actually another long shot: what happens if you use the phone in "safe mode". This is a mode that disables all user-installed apps - how you access it varies between devices, but I found some instructions for a different Umidigi phone so hopefully the same procedure will work.

The thinking here is that if it works OK in safe mode it will tell us that the problem isn't with the phone but with one of the apps. As I say, it's another long shot but it's just about imaginable.
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Thanks again for the new info, Hadron.

A bit more info that I gleaned this morning when I went out.

1) Left the house, with everything working perfectly (I'd disabled WiFi, so only relying on Mobile Connection)
2) Drove 4km to the shops: "No SIM Card" detected. As I watched, the Network Carrier would then be displayed in the top right corner with 4G Bars. But, within seconds it was gone & back to "No SIM Card".
3) Waited 5 minutes, still nothing.
4) Did a "Reset WiFi, mobile & Bluetooth".... Still nothing.
5) Did about 20' of shopping & didn't even look at the phone.
6) Back in the car, checked again: everything working fine. Could even watch LIVE football match in the street.
7) Drove into an underground carpark. Still everything working fine.
8) Came back to the car in the same underground carpark 30' later, "NO SIM Card"
9) Back home .. no problems at all.

I will definitely try the "Safe Mode" option. Can't believe I never tried that before. I'd seen that also mentioned elsewhere.

I've also bought a Start Up SIM for a different Network Provider & will give that a try.

Thanks again for taking the time to offer advice.
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But, when I go outside my home base, the signal drops out completely "NO SIM DETECTED". I cannot even make & receive calls. This happens all the time. Eventually, maybe after 10 minutes (making no changes to the settings), the SIM is finally detected. But, it might easily drop out. It's totally unreliable.

Thank you.

That sounds like the SIM card connection to the phone might be intermittent. Which could be a fault in the device itself. Because otherwise, a China phone like a Umidigi should work with Australian carriers no problem. Australia is not like the US, that has restrictive carrier activations, etc.
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Ok. It looks like the problem might be solved. Certainly, initial experimentation is positive.

The SIM I was using in my Umidigi phone was from an MVNO called "Amaysim" who onsells the Optus mobile network. I've used this MVNO for the past 8 years (with 2 different types of Samung phones) and had no problems. Family members use this MVNO with an Oppo phone & also no problems.

So, I thought I'd have no problems using my Amaysim SIM Card (with Optus mobile network) in my Umidigi phone.
But, it seems this is the issue.

Because, today, I purchased a different MVNO SIM which is linked to the Telstra network. And, problem solved!

I drove to the exact same spots where I had major issues over the past few weeks & the phone worked perfectly with the SIM connected to the Telstra network. The signal was strong. I could watch LIVE football streaming, YouTube streaming, make calls, send texts.

Now, it could just be coincidence, so I'll need to check more times over the next few days.

But, thank you to Hadron & mikedt for their help to fix the problem.

Much appreciated. Will test again over the next week & post the results.
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How was the experience? I don't understand anything about phones but i just experience something similar with Umidigi S5 Pro that i just purchased online. Occasionally it shows NO SIMCARD or NO SERVICE then comes back for a while. I tried thing like deleting sim toolkit cache and resetting network settings but nothing seems to work. Now i tried to disable IPv6 because it says fail on pinging host name...
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Hi ArmageddonXZ. I decided to take up the Umidigi offer to replace the S5 Pro with the Bison (8GB RAM). Absolutely no problems with the Bison. Works perfectly in every location where the S5 Pro would not work at all, or had unreliable connectivity.

I also changed my Mobile Provider (in Australia).

The only shame about the Bison is that is a very heavy phone. It's probably great for people who are using the phone in rough environments outdoors, or drop their phone a lot. But, I'd prefer the phone to be lighter. Also the Bison has extra short cut buttons on both sides, which are probably useful in the long term, but very annoying in the short term.

But, the most important point: the Bison works reliably when I'm out of the house &, for me, that's the most important aspect to any mobile phone.
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