Not receiving calls or texts

I’m using a Samsung S7, SM-G930FD, on T-mobile in the US. Occasionally calls don’t ring the phone, but go straight to voicemail. Sometimes texts never arrive. I’ve tested it by calling from another phone, and roughly 20% of the calls don’t come through. It seems to do better for a while after a reboot, but eventually it starts missing calls.

I’ve tried the same SIM card in another phone (also an S7, but a US model) and it works perfectly. The signal strength is good – 3 or 4 bars. I’ve cleaned the contacts on the card and blown out the card slot, in case it’s not making good contact, but that hasn’t helped.

One thing I’ve noticed is that when I install the SIM and turn on the phone, I immediately get a text from T-mobile saying “We see your phone does not have correct settings to access the internet or send MMS. Settings will be sent to your handset.” Could this have something to do with the problem, or would this only affect mobile data? Mobile data does work.

Any suggestions would be welcome. Thanks!
– oobleck

This is almost certainly because of the lack of VoLTE on the /e/Samsung.

See this for more info: Samsung S9 currently unusable in USA without VoLTE

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Thanks, that sounds like it might be the issue. But would that be so hit-or-miss? I would think if they’ve shut down non-VoLTE in my area that it wouldn’t work at all, and if they haven’t then it should work all the time.

I checked the IMEI with T-mobile’s IMEI checker and it said “This device is fully compatible with T-Mobile’s network technology.” Is the problem that /e/ doesn’t support VoLTE on this phone, even though the phone is capable of it?

I cannot comment on the real USA problem but are these messages ongoing? Does this make you think that the “new” settings are not being accepted or installed?

These settings are APN (access point names) they are critical for good performance and carriers are known to change them with evolving technology.

For your device to accept and alter APN it has been suggested that you might require a good wifi connection and good mobile data connection at the time that the new APN are applied.

I would suggest that if the messages are ongoing your carrier will know that you have an APN issue. (It might only affect MMS and be quite different from your main issue, idk)

The network is likely not static, but evolving as T-mobile makes adjustments to coverage. Additionally, you’re likely not standing in one spot 24/7, but moving across different tower areas, which might have different characteristics and different coverage. Maybe also, (speculating further) as you make calls the 3G telephony network has issues with relaying across different 3G areas and completing from end to end over 3G. And every individual call might not travel over the same route, even if the same two numbers are involved every time.

T-mobile is only verifying that the IMEI is one that corresponds to a device which is known to have been certified for VoLTE with their network. It’s not as if they’re peering into your hardware to verify that VoLTE is working. Those Samsungs originally had Samsung’s proprietary IMS/VoLTE application in-built, but they no longer do, because the custom ROM install wiped it out, and it cannot currently be re-implemented or replaced with a substitute. The T-mobile IMEI checker doesn’t “know” the operating system has been replaced.

Hope that helps, although it’s disappointing, I know.

I think this is fairly standard; when you insert a SIM, even if it has previously been used in the same phone, the carrier might send such a message, and then download the correct configuration to you over the air. They could word the message better, though.

When I put the sim in my old (stock) phone I get the text, and a message pops up in the status bar that allows me to install the settings, but that doesn’t happen on the /e/ phone. I guess it just installs them automatically. According to the guy at the local t-mobile store, if the mobile data works the settings must be correct, and the mobile data works fine.

The mobile data and MMS work fine, so I presumably the settings are correct. I always have good wifi and mobile data connections when I install the sim, since I do it at home.

Thanks for your helpful explanations. I guess I’ll have to go back to the stock rom so I can get the phone to work. At least, I hope that will work. Where is the best place to download a stock rom?

I’ve never done that, but here’s some basic info I found:

But don’t forget, you could just use the phone as a data-only device with /e/OS, and just set up to handle your calls, texts, and picture messages. (You already know that T-mobile won’t disallow your device, because for all they know, you do have operational VoLTE.)

That way you wouldn’t have to sacrifice your privacy like before.

But, bottom line, a Samsung is not a good option for a custom ROM when VoLTE is required by the network. Samsung doesn’t make it easy.

For a Samsung Odin3 for Windows is probably the easiest method to flash a Stock ROM, there are a number of sources of Samsung ROMs here What is a stock ROM and how do I get one?. There is also a Linux method using Heimdall.

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I have on my list of things to try. Thanks for the suggestion.


I’m new to flashing and so forth, as I’m sure you can tell. Can I use TWRP, which is already installed, to flash the stock rom, or does that have to be done via Odin? Googling found some people saying yes and others saying no.

People with experience can do remarkable things, but in recommending a robust course of action, I would propose that Odin is the safest way to proceed ! There are many guides to Odin out there, I suggest you do not commit until you have a set of instructions you feel is reliable and understandable – and of course don’t put unrealistic time limits on yourself, learning takes time.

Good luck

Thanks, I’ll go with the tried-and-true Odin method.