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I have got a Huawei 4G LTE USB modem and have successfully connected and activated it in Ubuntu 20.04. I can use the data connection from a SIM card, but I haven't got the SMS as well as other functionalities such as USSD to work yet.

I came to know about a software called ModemManager GUI, but it too cannot send and receive SMS and USSD codes. It shows an error while sending SMSs: enter image description here

Same for USSD: enter image description here

I need at least one of these features to know my current data balance. How can I proceed?

Puspam
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1 Answers1

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It is possible modemmanger does not support sms or ussd for this modem. another way to check ussd and sms is to use picocom by giving AT commands.

install picocom:

sudo apt install picocom

to be able to issue the AT commands you would have to disable the internet connection to free the modem

next find out the various ports of the modem: ls /dev/ttyU*

usually you would be presented with three ports;

dialogue port (ie 1st port) is /dev/ttyUSB0
audio  port (ie 2nd port) is /dev/ttyUSB1   (audio and microphone if supported)
sms & internet aka data  port (ie 3rd port) is /dev/ttyUSB3

start picocom on the dialogue port:

sudo picocom -c /dev/ttyUSB0
the -c means local echo on, making AT commands visible as you type

now check USSD:

AT+CUSD=1,"*333#"

sometimes the response may be in unreadable characters. to correct that, before issuing the ussd command, you would have to set the modem to gsm mode with 

AT+CSCS="GSM"

followed by the ussd command

ptetteh227
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  • Should I type those AT commands while picocom is running? In the same terminal? – Puspam Jun 06 '20 at 09:15
  • yes. type them while picocom is running – ptetteh227 Jun 06 '20 at 13:27
  • But, it constantly prints something or the other, it does not let me type something. – Puspam Jun 06 '20 at 14:55
  • if possible kindly copy and paste the errors or warnings you are getting – ptetteh227 Jun 06 '20 at 18:03
  • Here is the output after running sudo picocom -c /dev/ttyUSB0 : image – Puspam Jun 07 '20 at 09:10
  • These lines are being printed again and again with an interval of 1 second: `^SYSINFOEX:2,3,0,1,,6,"LTE",101,"LTE"

    OK

    ^HCSQ:"LTE",62,54,181,24

    ^RSSI:28

    ^HCSQ:"LTE",64,54,176,20

    ^HCSQ:"LTE",61,53,181,22

    +CSQ: 27,99`

     – Puspam Jun 07 '20 at 09:14
  • @Puspam you could still go ahead and type it (better still do a copy and paste) then press Enter. disregard the lines that are being printed. if it don't work start picocom on the other ports availble from ls /dev/ttyU* – ptetteh227 Jun 07 '20 at 19:33
  • Thanks for the idea. But now, after I enter AT+CUSD=1,"*333#" it gives +CME ERROR: 100. It happens even if I run AT+CSCS="GSM" before that. I have only two tty ports available and none of them worked. – Puspam Jun 08 '20 at 08:01
  • hm. pls try again with the internet disconnected – ptetteh227 Jun 09 '20 at 09:34
  • Tried it, but still the same problem +CME ERROR: 100. – Puspam Jun 11 '20 at 10:45