# Asterisk Project : What to Download?

Added by malcolmd , edited by mdavenport on Nov 04, 2010

On a typical system, you'll want to download three components:

- Asterisk
- DAHDI
- libpri

The libpri library allows Asterisk to communicate with ISDN connections. (We'll cover more about ISDN connections in Section 450.8, "Intro to ISDN PRI and BRI Connections".) While not always necessary, we recommend you install it on new systems.

The DAHDI library allows Asterisk to communicate with analog and digital telephones and telephone lines, including connections to the Public Switched Telephone Network, or PSTN. It should also be installed on new systems, even if you don't immediately plan on using analog or digital connections to your Asterisk system.

DAHDI

DAHDI stands for Digium Asterisk Hardware Device Interface, and is a set of drivers and utilities for a number of analog and digital telephony cards, such as those manufactured by Digium. The DAHDI drivers are independent of Asterisk, and can be used by other applications. DAHDI was previously called Zaptel, as it evolved from the Zapata Telephony Project.

The DAHDI code can be downloaded as individual pieces (dahdi-linux for the DAHDI drivers, and dahdi-tools for the DAHDI utilities. They can also be downloaded as a complete package called dahdi-linux-complete, which contains both the Linux drivers and the utilities.

Why is DAHDI split into different pieces?

DAHDI has been split into two pieces (the Linux drivers and the tools) as third parties have begun porting the DAHDI drivers to other operating systems, such as FreeBSD. Eventually, we may have dahdi-linux, dahdi-freebsd, and so on.

The current version of libpri, DAHDI, and Asterisk can be downloaded from http://downloads.digium.com/pub/telephony/.