PSTN trunks
A Public Switched Telephone Network (PSTN) trunk is an old-fashioned analog Basic Rate Interface (BRI) ISDN or Primary Rate Interface (PRI) phone line. 3CX can use any of these with the correct analog to SIP gateway. Usually, these come into your home or business through a pair of copper lines. Depending on where you live, this may be the only means of connecting 3CX and communicating outside of your network.
One of the advantages of a PSTN line is reliability and great call quality. Unless the wires break, you will almost always have phone service. However, what about call quality? After all, many people would like to have a comparison between VoIP and PSTN.
Analog hardware for BRI ISDN and PRIs will be discussed in greater detail in Chapter 9. For using an analog PSTN line, you will need an FXO gateway. There are many external ones available. Until Sangoma introduced a new line at the end of 2008, there had not been any gateway that worked inside a Windows PC with 3CX. There...