Try mmcli -m any and look for a section toward the bottom that contains those.
And I was mistaken about your phone number being displayed… That’s in Android. The command output does show your IMEI, though.
Look for “operator id” and “operator name.”
Yep, 310260 when connected to Mint. On the money.
The phantom signal reports 310410.
Can I tell the modem to only recognize 310260?
Sure! With the APN setting. 
Going to the MCC MNC list website, sorting on MCC, then searching “410” reveals that it’s AT&T.
Is the phantom signal still there if you unplug or turn off the extender?
Does Mint roam on AT&T when there’s weak T-mobile signal? (doubtful)
Has the manufacturer of your extender partnered with AT&T to provide range?
Was the extender provided by T-mobile?
This is getting exciting. Progress is being made here…
I have tried this. I apparently am not skilled enough. How exactly to I make the modem only recognize Mint/310/260 only?
As I type this, my modem has probably jumped from one signal to the next 3-5 times. Sometimes it goes right back to Mint, sometimes it doesn’t. Drives me nuts.
Going to the MCC MNC list website, sorting on MCC, then searching “410” reveals that it’s AT&T.
Sounds good.
Is the phantom signal still there if you unplug or turn off the extender?
Yes, although I need to confirm the same MCC
Does Mint roam on AT&T when there’s weak T-mobile signal? (doubtful)
I do not believe so.
Has the manufacturer of your extender partnered with AT&T to provide range?
I doubt it. It is a generic Yagi antenna unit from Amazon.
Was the extender provided by T-mobile?
No. Again, a generic Yagi antenna.
I was being facetious about the APN. The modem is only going to connect to the network that your SIM/provider authorizes, and what you see with the mmcli command is what the modem is connected to, not other signals that may be present in the area.
Maybe Mint does offer domestic roaming, and maybe that’s why your connection fluctuates between T-mobile and AT&T towers. Try to get the phantom signal again, leave your phone in that spot, turn off the extender, return to the phone, and run the mmcli again, just to see if the phantom signal is still there. If so, it must be something that Mint is doing to provide uninterrupted service to you. If not, then it’s likely that the extender is connecting your T-mobile signal to AT&T towers for some reason.
Ah. Bummer on the APN.
Ok. I will try that. I believe the other signal will persist given my testing over the last week. The phantom/AT&T signal has been around for a long time. I noticed it well-before the extender experiment commenced.
If the issue does persist, I should probably look for a T-Mobile only extender? Would that be correct? I do not know if those even exist.
Did Mint/T-mobile approve the extender for your use?
Just taking a quick look at an extender on Amazon, it states that it works for all the major U.S. networks.
Once you set the APN (or if it’s auto-set when you power on with the SIM), it should stay active; it can’t arbitrarily connect to any networks it’s not authorized to connect to.
Another experiment:
Put your SIM into your Android, download* the Network app from F-Droid, launch it, and walk around the house, observing what it connects to. (This one does adjust in real time as you move around.) Try it both with the extender on and with it off. See if you still connect to the phantom AT&T network.
*… or you can just run the service code for your particular Android device to see the same info.
Hello. No, no approval given by Mint or T-Mobile.
I can try more experiments. I can report back on the Android efforts - which I was trying to avoid in the first place but I appreciate what you are saying.
I think the phantom network gets “found” whenever the Mint signal gets dropped. And back and forth and back and forth.
I read on one product on Amazon that carrier approval is required, and that they typically grant it without question. Might wanna check the documentation for your product.
This is exactly the same kind of behavior I am experiencing. The modem is trying to connect to another carrier, like it’s ignoring the SIM or something. Can you contact support about this and send them some logs and reference me, because they were really stumped with my issue. They were suggesting it was an antenna issue but I don’t think so, I’ll get full bars but it just says Cellular in the pull down indicator and not the name of my carrier.
I can try that. The odd thing is this modem behavior only really happens at home with a weak signal. I have good 4G coverage in town, on the highway, and at work. I should add that I live in a rural area, in a valley, underneath trees.
I wanted to follow-up on this issue: I try to “set” the APN to Mint in the “Network” setting in the GUI for “Mobile”, I get this message:
GDBus:Error.org.freedesktop.ModemManager1.Error.Core.WrongState: CannotRegisterModem: modem is connected
Is that error message meaningful?
Not that it matters much, but I am also bouncing around to a new phantom signal! I am also showing a lot of 311480 which is Verizon.
The issue I believe I am having is that the “booster” or “amplifier” just picks up every carriers signal. Fortunately, it is doing its job. Unfortunately, the Librem 5 refuses to stick to one signal - Mint/T-Mobile.
To someone who understands it, yes. (Not me. Lol.)
But I have seen it many times. I think it will go away on its own and self-correct.
Fair enough, you have provided enough support that I do not deserve. I will reach out to Purism.
Maybe your carrier has to first associate your SIM with the device you’re using; could have something to do with getting their approval to use the extender on the network.
I will try that again with Mint and maybe call them. However, I wanted to express a thought here that I have had many times:
The previous wifi card in the Librem 5 was clearly inferior and it was upgraded to a clearly superior SparkLan card. My opinion: the BM818 modem is something and certainly something trending towards inferior. Is it not possible to replace it? I just opened up the back of my phone. There it is. I could just take some wires off it and pop it out and pop another one in. Easy peasy.
Seriously, is there a way to look into a better cellular modem?
