How to check cellular connectivity? - NetNinja

How to check cellular connectivity? - NetNinja

Having issues connecting to your device using the cellular connection?

In some cases due to building materials or other radio frequency (RF) interference it's possible service might be degraded. You can check what the modem reports for signal by using the below commands. 

GSM modems can be controlled by a number of different protocols. Because of this, NetworkManager uses a second component called ModemManager to interface with them.

On the NetNinja, we can do this:

  1. $ mmcli -L
      /org/freedesktop/ModemManager1/Modem/0 [Sierra Wireless, Incorporated] EM7455

From here, I see that the current modem number is 0.

To query the status of the modem, just specify the -m option to select the modem you wish to query

  1. $ mmcli -m 0
  --------------------------------
  General  |            dbus path: /org/freedesktop/ModemManager1/Modem/0
           |            device id: <redacted>
  --------------------------------
  Hardware |         manufacturer: Sierra Wireless, Incorporated
           |                model: EM7455
[...various information omitted ...]
  --------------------------------
  Status   |                 lock: sim-pin2
           |       unlock retries: sim-pin (3), sim-pin2 (3), sim-puk (10), sim-puk2 (10)
           |                state: registered
           |          power state: on
           |          access tech: umts
           |       signal quality: 59% (recent)
  --------------------------------
[...more information...]

Depending of the model of your GSM modem, you may also be able to set up extended signal information reporting:

First set the signal refresh-rate if when you run the command you get 0 seconds refresh rate, then run it again to grab signal information. 
  1. $ mmcli -m 0 --signal-get
  ----------------------
  Signal | refresh rate: 0 seconds

$ mmcli -m 0 --signal-setup=10
Successfully setup extended signal information retrieval

$ mmcli -m 0 --signal-get
  ----------------------
  Signal | refresh rate: 10 seconds
  ----------------------
  UMTS   |         rssi: -77.00 dBm
         |         ecio: -3.50 dB

How to decode signal strength.

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