This should work with Quectel modules such as EC20, EC21, EC25, EG9x and Simcom sim7600 and possibly other models with voice over USB capability. Tested with the EC25-E mini-pcie module and Waveshare sim7600 g-h dongle. If the product page of your Quectel module contains the application note Voice over USB and UAC or Voice over UAC, you should be good to go. Praise God! Have been able to integrate ALSA support for UAC mode, steps to use UAC can be found here If using Quectel serial audio port, please ensure gps messages has been turned off with AT+QGPSCFG="outport","none"
Note for Pi users: If using a Pi and especially a device older than Pi4, you will invariably have problems of various kinds if powering the modem using a Pi usb port due to the current limiting circuit (600ma - 1.2A). Even with a Pi 4, you will not be able to stably handle modem devices with a larger power draw (2.1A) than that of the waveshare sim7600 dongle. You will need to provide independent power to the modem without using the Pi usb port which must only be used for data communication. If the modem device is a Pi HAT, you can provide power by stacking and using a beefy power supply.
I'm not a C programmer at all and this write-up may help those interested in improving this driver and also for supporting other modules such as those from Telit, U-blox, Sierra Wireless etc.
A key part is understanding call handling by the driver. Everything revolves around URCs (Unsolicted Result Code) received at the modem terminal when certain events occur. So for Huawei when dialling out an ^ORIG URC is generated, when an outgoing or incoming call is connected there appears a ^CONN URC and when a call is terminated by either party a ^CEND URC is received. The RING URC for incoming calls is universal but all the others mentioned are specific to Huawei and appropriate changes are to be made in at_response.h and at_response.c to handle calls correctly.
In many modules, when AT^DSCI=1 is set, URC for call status indication is generated. For example the URC ^DSCI: 4,1,3,0,+XXXXXXXXX,145 indicates that an incoming voice call has been connected. The URC ^DSCI: 3,0,6,0,XXXXXXX,129 indicates an outgoing voice call has terminated. ^DSCI can be activated on modules by many manufacturers such as Quectel, Simcom, Telit, Sierra Wireless etc. There may be some differences, for example my Simcom 7600 module does not generate the call termination URC.
Armed with this knowledge and using AT^DSCI=1 as an intialization command, we can now set up the Huawei ^ORIG URC here to handle entire call management (initiatiing, connecting in or out, terminating) through code block here with necessary changes.
Simcom was very tricky to get working as there is no proper call termination URC and its serial audio port also does not play well with the chan_dongle code. But thanks to God, was finally able to get it working. Still remains a hack job as call ids cannot be matched for termination. If your call ids are different from 1,2,3 or 4 for outgoing and incoming calls, you'll need to make changes in this block here
Way forward: This justified rant by a professional in the industry points out that the virtual sound card solution is the way voice should be provided. We can already see that in few modules from Quectel, Telit, u-blox, Sierra Wireless etc. With very few changes in code, non-Quectel modules with USB audio can most probably be accommodated. Please get in touch in the discussions thread on this topic if you have such a module.
Those with problems with chan_mobile with certain bluetooth controllers such as the in built Raspberry Pi one may find a solution here
Thanks be to the Father of Lights from Whom are all good things.
In these days of great darkness, when truth and justice are outlawed and where believers themselves are greater obstacles than the atheists with their bigotry, hatred, self-righteousness, falsehood and pride you may just find God speaking to you through this random message to Vassula https://ww3.tlig.org/en/the-messages/messages-random/ or a random verse from the bible www.sandersweb.net/bible/verse.php
I do not need donations, but if you wish you could donate to the person I've forked this from. Or if so inclined, you could donate here https://bethmyriam.org/
$ ./bootstrap
$ ./configure --with-astversion=16.20
$ make
$ make install
copy quectel.conf to /etc/asterisk Change context and audio serial port as required
If you run a different version of Asterisk, you'll need to update the
16.20 as appropriate, obviously.
If you did not make install Asterisk in the usual location and configure
cannot find the asterisk header files in /usr/include/asterisk, you may
optionally pass --with-asterisk=PATH/TO/INCLUDE.
WARNING: This example uses the raw SMS message passed to System() directly. No sane person would do that with untrusted data without escaping/removing the single quotes.
[quectel-incoming]
exten => sms,1,Verbose(Incoming SMS from ${CALLERID(num)} ${BASE64_DECODE(${SMS_BASE64})})
exten => sms,n,System(echo '${STRFTIME(${EPOCH},,%Y-%m-%d %H:%M:%S)} - ${QUECTELNAME} - ${CALLERID(num)}: ${BASE64_DECODE(${SMS_BASE64})}' >> /var/log/asterisk/sms.txt)
exten => sms,n,Hangup()
exten => ussd,1,Verbose(Incoming USSD: ${BASE64_DECODE(${USSD_BASE64})})
exten => ussd,n,System(echo '${STRFTIME(${EPOCH},,%Y-%m-%d %H:%M:%S)} - ${QUECTELNAME}: ${BASE64_DECODE(${USSD_BASE64})}' >> /var/log/asterisk/ussd.txt)
exten => ussd,n,Hangup()
exten => s,1,Dial(SIP/2001@othersipserver)
exten => s,n,Hangup()
[othersipserver-incoming]
exten => _X.,1,Dial(Quectel/r1/${EXTEN})
exten => _X.,n,Hangup
exten => *#123#,1,QuectelSendUSSD(quectel0,${EXTEN})
exten => *#123#,n,Answer()
exten => *#123#,n,Wait(2)
exten => *#123#,n,Playback(vm-goodbye)
exten => *#123#,n,Hangup()
exten => _#X.,1,QuectelSendSMS(quectel0,${EXTEN:1},"Please call me",1440,yes,"magicID")
exten => _#X.,n,Answer()
exten => _#X.,n,Wait(2)
exten => _#X.,n,Playback(vm-goodbye)
exten => _#X.,n,Hangup()
Call using a specific group:
exten => _X.,1,Dial(Quectel/g1/${EXTEN})
Call using a specific group in round robin:
exten => _X.,1,Dial(Quectel/r1/${EXTEN})
Call using a specific quectel:
exten => _X.,1,Dial(Quectel/quectel0/${EXTEN})
Call using a specific provider name:
exten => _X.,1,Dial(Quectel/p:PROVIDER NAME/${EXTEN})
Call using a specific IMEI:
exten => _X.,1,Dial(Quectel/i:123456789012345/${EXTEN})
Call using a specific IMSI prefix:
exten => _X.,1,Dial(Quectel/s:25099203948/${EXTEN})
How to store your own number:
quectel cmd quectel0 AT+CPBS=\"ON\"
quectel cmd quectel0 AT+CPBW=1,\"+123456789\",145
quectel reset <device>
quectel restart gracefully <device>
quectel restart now <device>
quectel restart when convenient <device>
quectel show device <device>
quectel show devices
quectel show version
quectel sms <device> number message
quectel ussd <device> ussd
quectel stop gracefully <device>
quectel stop now <device>
quectel stop when convenient <device>
quectel start <device>
quectel restart gracefully <device>
quectel restart now <device>
quectel restart when convenient <device>
quectel remove gracefully <device>
quectel remove now <device>
quectel remove when convenient <device>
quectel reload gracefully
quectel reload now
quectel reload when convenient