System information

When installing telephony hardware, be sure you update the /etc/dahdi/
modules file to enable the appropriate modules for your hardware and
then reload DAHDI with the init script (/etc/init.d/dahdi). You can use
the dahdi_genconf modules command to generate the modules file for
your system as well.
Most PRI circuits in North America will use a T1 with the following characteristics:
• Line code: B8ZS (bipolar with 8-zeros substitution)
• Framing: ESF (extended superframe)
You will need to configure two files. The /etc/dahdi/system.conf file should look some-
thing like this:
loadzone = us
defaultzone = us
span = 1,1,0,esf,b8zs
bchan = 1-23
echocanceller = mg2,1-23
hardhdlc = 24
And the /etc/asterisk/chan_dahdi.conf file should look like this:
[trunkgroups]
[channels]
usecallerid = yes
hidecallerid = no
callwaiting = yes
usecallingpres = yes
callwaitingcallerid = yes
threewaycalling = yes
transfer = yes
canpark = yes
cancallforward = yes
callreturn = yes
echocancel = yes
echocancelwhenbridged = yes
relaxdtmf = yes
rxgain = 0.0
txgain = 0.0
group = 1
callgroup = 1
pickupgroup = 1
immediate = no
switchtype = national ; commonly referred to as NI2
context = from-pstn
group = 0
echocancel = yes
PSTN Circuits | 139