Hi, have modified chan_dongle code here that can be used with Asterisk for Quectel and Simcom modules. With very few changes, I think it should be possible to get Sierra Wireless modules (those with voice and usb audio capability) also to work. Modules like WP76xx and EM/MC73XX should be compatible I think.
If any user has these or other modules with USB audio ( I do not own any) and would like to get it working with asterisk, please get in touch here. You must be comfortable working with a linux vm, asterisk and a modem terminal program like minicom or putty. Please make sure that calls work on your modem and you are able to redirect audio to USB and record voice using something like Audacity.