I was able to make calls using my RPI 3 model B+, Huawei E153 GSM Modem, and minicom.
I can see that the cellphone I'm calling was able to answer my call (from my Pi). I plugged in my headphones to the RPI but I can't hear any sound. Even if I talk the other party can't hear me.
I should mention I connect to my Pi via SSH and that's where I run minicom and issue AT commands.
I wonder what else should I do?
If you're trying to make a call using ATD, ATA or ATS0 commands, bear in mind that these commands instruct the modem to make a call using its own audio inputs/outputs. They will work as expected if your modem is a mobile phone (and you will be able to speak to / hear the other side using the phone), but they will do nothing on a device which provides only data. They are there just for compatibility reasons.
Plugging a microphone and a speaker into the RPi will not help.
