Some pointers that might be useful: https://beej.us/guide/bgnet/ https://beej.us/guide/bgnet/ https://github.com/srsLTE/srsLTE https://github.com/srsLTE/srsLT

Some pointers that might be useful: https://beej.us/guide/bgnet/ https://beej.us/guide/bgnet/ https://github.com/srsLTE/srsLTE https://github.com/srsLTE/srsLTE https://www.gnuradio.org/grcon/grcon17/presentations/open_first/Paul-Sutton-SRS-OpenFirst.pdf https://www.gnuradio.org/grcon/grcon17/presentations/open_fi... https://en.wikipedia.org/wiki/Asterisk_(PBX) https://en.wikipedia.org/wiki/Asterisk_(PBX) Don’t be afraid to study the source code if you’re curious about the inner workings of a system. Best of luck!