Generate automatic voice calls with Raspberry pi and SIM900 GSM module
Raspberry Pi 3
SIM900 Arduino GSM shield
USB TTL converter (CH340G)
AUX cable
USB TTL converter is used to transmit data between RPI3 and SIM900
Audio OUT of the RPI3 is connected to Audio IN of SIM900
Install minicom and check the GSM module with some ATcommands to ensure the right connection
sudo apt-get install minicom
Enable CLCC
making a call
sudo apt-get install mpg321
sudo pip install pathlib
sudo pip install gTTS
sudo apt-get install alsa-utils
sudo apt-get install alsa-oss
How to run python program
Change directory to the location where python script exists
Run: sudo python call.py +9471XXXXXXX "your message"
Note: Voice was too noisy at first, as the solution, GSM module powered using an external power supply. Then ground pin of GSM module is connected to RPI ground and eventually annoying noise got removed.