Mine

not working config to get 20 lines//
--------------------
loadzone=au
defaultzone=au
span=1,1,0,ccs,hdb3,crc4
bchan=1-15,17-21
dchan=16

[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

-------------------------------------------------

working config to get 10 lines

loadzone=au
defaultzone=au
span=1,1,0,ccs,hdb3,crc4
bchan=1-10
dchan=16








[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               => 1-10