Mine

[channels]
switchtype            = euroisdn
context               = from-pstn
signalling            = pri_cpe
echocancel            = yes
echocancelwhenbridged = yes
echotraining          = yes
txgain                = -4.00
rxgain                = -1.0
group                 =  1
usecallingpres        = yes
amaflags              = default
musiconhold           = default
channel               => 1-15, 17-21


loadzone=au
defaultzone=au
span=1,1,0,ccs,hdb3,crc4
bchan=1-15, 17-21
dchan=16