In this chapter we saw all that's related to interfacing FreeSWITCH directly to PSTN, both for originating and for terminating calls.
First of all we made a tribute to one of Jim Dixon's great contributions to Open Source - Open Hardware Telecommunication, the Zapata Telephony project.
We found out how to configure the FreeTDM library and module for FreeSWITCH usage, how to interact with DAHDI drivers, and how to install Sangoma libraries (Sangoma being a major corporate sponsor of FreeTDM).
We covered all of the many different current and legacy protocols for PRI, FXO/FXS, trunking, and so on.
We then delved into practical usage in the FreeSWITCH operation, both dialplan and debugging troubleshooting levels.
That's really all you may possibly want to know about PSTN and TDM.