Please read this before seeking help

[IchthysMaranatha]

Please make sure calls work with your modem without Asterisk and you've carried out the testing on test bed on vm with PC/laptop before raising an issue here. Note for those using a Pi and having problems; it is almost certainly due to pi usb power issues. To resolve, provide independent power to modem device eliminating power draw from Pi's usb port.

To test calling, you can use something like minicom or dterm with linux or putty or hyperterminal with Windows.
Here are the steps to test with putty on Windows
First install necessary Windows usb drivers for your device, Quectel or Simcom as the case may be
Connect your device to the USB port, your device should now show up under ports in device manager. Note the port no for AT commands.
Run putty, set connection type as serial, speed as 115200 and put in the COM port no that shows up in your device manager for at commands in serial line. For me, it's COM3 for Quectel and COM10 for Simcom.

Place an incoming call and you should see the RING URC coming up on putty. You should be able to answer call with ata. You should be able to place an outgoing call with atd9999999; replace 9999999 with your desired no and do not omit the semicolon at the end.

If you wish to test using minicom on linux, this might help https://www.thegeekstuff.com/2013/05/modem-at-command/

If you plan to use the serial audio port of a Quectel device rather than UAC, you'll need to disable the use of the port for gps. Run the following command in putty
AT+QGPSCFG="outport","none"

If calls are not working you'll need to sort it out with your telecom provider and/or modem vendor. You can seek help on the Quectel forum https://forums.quectel.com/ if it's a Quectel device.

If calls are working and you are still unable to use chan_quectel, please proceed to test bed testing as outlined here

[IchthysMaranatha]

Windows drivers may be available here
Quectel https://forums.quectel.com/t/quectel-ec25-eu-win10-64b-drivers/8599
Simcom https://github.com/elementzonline/GSMModem/tree/master/SIM7600/Drivers