Librem 5, Cellular Network Testing

I have decided to try, again, to make my home cellular network work better on my Librem 5. (I have more free-time during this snowy holiday season). In my high-tech web research, I am exposed to suggestions very similar to this: “download the “Network Signal Info” or “Open Signal” app on your Android or IOS device and test from there.” The problem? I own a Librem 5 with a Linux operating system.

I bought a cheap network signal enhancer and it does, kind of, work. I have run cabling, etc. I have a “booster”. However, I am having difficulty doing any cogent testing of signal strength, etc, based on where I put the antenna. I am relagated to switching my Mint mobile SIM to my old Android device and testing from there. That is silly.

Any thoughts on how to test cellular signal strength so that I can troubleshoot this issue using only my linuxy Librem 5?

Much appreciated for any help anybody might provide.

I just checked with a script I wrote a while back, and I see that it shows my LTE “signal quality” as a percentage that differs according to the L5’s location inside my house.

Does that serve your purpose?

  1. This is super cool. Thank you. 2. I don’t know if it will resolve my situation but I am sure it will not hurt my situation. I think the “walking around the house and percentage of strength indication” will certainly not hurt.

I will report back once testing has been commenced. Thank you!

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Note that sometimes the % shows “(cached)” and sometimes “(recent)” so you might need to restart, and it doesn’t adapt as you walk around. You’ll have to run the command from each location.

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Interestingly, my phone tells me that it registers a LTE, 4G signal at around 40-60%. However, my Mint card (T-Mobile) does not show up as the “Network Type”. Am I testing that signal or can I test only T-Mobile? Stated differently, can I differentiate between what signal or network I am picking up? I have no idea what this phanton LTE 4G signal apparently is. It doesn’t register for me. I suppose it could be Verizon. I do not know.

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I, too, have service from an MVNO that uses T-mobile’s network, and the command always shows T-mobile as the LTE signal for me. Could yours be showing something related to your network signal enhancer?

Otherwise, the displayed MCC+MNC code might help you identify the source of your signal:

(P.S. I know for a fact that there are other strong LTE signals in my area besides T-mobile.)


Is there a reason I cannot access that website from my home wifi network? I am getting an “not secure” error. I am assuming I have a firewall of some kind.

Never mind I just used a Tor browser.

Can you elaborate on what this is? e.g. make/model

If you are interested in the cellular network signal strength then the magic AT command is

The response will be
where n is the number you are interested in.

n will either be 99 (unknown) or it will be a number in the range 0 to 31 where 0 is weakest and 31 is strongest. (Can be converted arithmetically to a dBm value but that conversion may hinder rather than help here so details omitted.)

Tips & Tricks · Wiki · Librem5 / Librem 5 Community Wiki · GitLab

I imagine that mmcli -m any | grep 'signal quality' is giving you the same information except that

  • mmcli is converting the actual number from the modem into some other numeric representation
  • mmcli may sometimes give you a cached value (which probably doesn’t suit the purpose).

Is that Linuxy enough? :slight_smile:


This is very Linuxy. I will try some of what you suggest and report back.

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Ok. Your tool was very helpful. I improved the cellular service at home. Not perfect, but an improvement.

One odd problem I now have is I get no ring tone when I call someone. It is very disconcerting to not hear a ring tone when calling.

Anybody else have no ring tone when calling? Anybody solve this?


Previously reported: Report: No ringing on my end when placing outbound calls, but the call goes through


Crimson fix? Very oddly, I get a ring tone when I call using Odd.


I am still playing with my poor at-home cellular coverage. I have some home coverage now but another odd issue persists: my cellular modem keeps picking up a different signal and (I believe), because it is stronger than my Mint/T-Mobile Signal, it switches to the stronger signal, consistantly. Very annoying.

Is there a way to point the modem at only a particular “signal” - e.g.: the signal I want it to recognize and use?


Are you still able to make a call or does the phone deregister? I’m asking because I’m having this issue where in some places in my area it’s not registering but I get sometimes full bars. It’s very odd, and the reason I’m sending my phone back again to Purism.

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I don’t think the command would show anything but the mobile network that the modem is connected to, and it can only connect to the network that corresponds to your SIM card.

In fact, you should see your phone number IMEI displayed in the output.

Which MCC and MNC designators are showing in the output?

My money is still on the signal that your extender is emitting, as I mentioned earlier.

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Are you asking for that information when I am connected to the Mint network or without connection or both?

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When you see the unidentified LTE signal.

T-mobile/Mint/etc. should be something like 310 and 260 (or 240, etc.).

I don’t know anything about extenders, but isn’t it acting sort of like a bridge or access point, except instead of WiFi, it’s the mobile network…? When you’re connecting to the extender, it might show something other than Mint/T-mobile.

Could your extender be a clandestine surveillance device produced and controlled by a foreign nation? :rofl: :no_mouth:

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I can make a call when the phone says I am connected to Mint. Not on the other signal.

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Thank you for all your help. What command output do you mean? I don’t see a MCC or MNC designation using mmcli --modem=X

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I knew it. I just needed someone to confirm it.

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