System information

Figure 9-3. A balun
Analog connections vary massively from place to place—you will know what kind of
connector is used in your locality. The important thing to remember is that the analog
line is only two wires, and these need to connect to the middle two pins of the RJ11
plug that goes into the Digium card—the other end is the local one. Figure 9-4 shows
the plug used in the UK, where the two wires are connected to pins 2 and 5.
Figure 9-4. The BT plug used for analog PSTN connections in the UK (note only pins 2–5 are present)
The Digium Asterisk Hardware Device Interface, or DAHDI, actually covers a number
of things. It contains the kernel drivers for telephony adaptor cards that work within
the DAHDI framework, as well as automatic configuration utilities and test tools. These
parts are contained in two separate packages (dahdi-linux and dahdi-tools), but we can
also use one complete package, called dahdi-linux-complete. All three packages are
available at http://downloads.digium.com/pub/telephony/. The installation of DAHDI
was covered in Chapter 3.
Chapter 7 covered the use of analog and digital PSTN connections, and we will not
reiterate those details here. If you are using digital PSTN connections, your job is to
find out what sort of connection the telco is giving you. Generally, if you have requested
186 | Chapter 9: Internationalization