DAHDI is a collection of open source drivers, for Linux, that are used to interface with a variety of telephony related hardware. It consists of two parts. The DAHDI-Linux project contains the individual board drivers for the supported hardware.. 

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Abbreviation: 
● D – Digium
● A - Asterisk
● H – Hardware
● D – Digital
● I – Interface

It is the replacement for the Zaptel drivers that allow for interfacing Asterisk with TDM/PSTN interface cards from multiple vendors as well as allowing for hardware timers for meetme, MusiconHold and IAXtrunks.

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