Test GSM Modem Using minicom

If you want to test your GSM modem before running any application such as SMS gateway, a lightweight application called minicom can be used for this purpose.

To install minicom, run yum:

yum install minicom
After installing, create a symlink called /dev/modem to your serial or USB device. In this example, my GSM modem is detected and given the device name /dev/ttyS0, so:
ln -s /dev/ttyS0 /dev/modem
You need the symlink because minicom, by default, will use the device /dev/modem. If you have a USB device, it could be detected as /dev/ttyUSB0 or /dev/ttyACM0, depending on your setup.
Once you have your symlink ready, setup minicom by running:
minicom -s
You can use the next screen to setup your modem. In my case, I just need to setup the baud rate to 115200:

â Filenames and paths      â

â File transfer protocols  â

â Serial port setup        â

â Modem and dialing        â

â Screen and keyboard      â

â Save setup as dfl        â

â Save setup as..          â

â Exit                     â

â Exit from Minicom        â


I selected Serial port setup -> E -> I
Then pressed Esc to fall back to minicom.
At the minicom screen, type the following commands to test SMS sending:


You should get: OK


You should get : +CREG: 0,1


You should get: OK


You should get: OK

If all above commands executed without errors, try sending a test SMS by running:

> Testing

Exit the data sending part by pressing CTRL+z

You should get: +CMGS: 23

If not, try re-formatting the number to use the format + (do not forget the + sign).

You should now receive your test SMS to mobile number +639991234567.