I would like to understand how to handle digital voice on gsm modules.
After reading 3gpp gsm mux 07.10 specification it is my understanding that gsm modules can be configured to transport voice frames on dedicated channels (DLC) sending a SNC frame with bit3 set on.
I considered to use simcom sim900 module but official documentation indicates that SNC frames are not supported.
Are DLCs channels the right approach to send&receive voice frames? is there another way to do it (PCM, PWM, I2S interfaces)?