Link Spam1 ao modem Oi.
Rx –> TX
Tx –> RX

Link Spam 2 ao PABX Leucotron
RX –> RX
RX–> Tx

/etc/asterisk/chan_dahdi.conf
[trunkgroups]
[channels]
language=br

usecallerid=yes
callwaiting=yes
usecallingpres=yes
callwaitingcallerid=yes
threewaycalling=yes
transfer=yes
canpark=yes
cancallforward=yes
callreturn=yes
echocancel=yes
echocancelwhenbridged=no
overlap=yes

signalling=mfcr2
mfcr2_variant=br
mfcr2_get_ani_first=no
mfcr2_max_ani=20
mfcr2_max_dnis=4
mfcr2_category=national_subscriber
;mfcr2_metering_pulse_timeout=4000

mfcr2_allow_collect_calls=yes
mfcr2_double_answer=no

context=rotasaida
group=1
channel=>1-15,17-31

mfcr2_metering_pulse_timeout=4000
mfcr2_max_ani=20
mfcr2_max_dnis=20
context=from-internal
group=2
channel=>32-46,48-62

===================================================

/etc/dahdi/system.conf
loadzone = br
defaultzone=br

span=1,1,0,cas,hdb3
span=2,0,0,cas,hdb3

cas=1-15,17-31:1101
cas=32-46,48-62:1101

==============================================

/etc/asterisk/extensions.conf
[general]
static=yes
writeprotect=no
autofallthrough=yes
clearglobalvars=no
priorityjumping=no

[globals]

[rotasaida]
;mandando tudo que sai de uma spam para outra. Da spam 1 para spam 2
exten => _X.,1,Noop(${EXTEN})
exten => _X.,2,Dial(DAHDI/g2/${EXTEN})

[from-internal]
;enviando tudo que entra na spam 2 para spam 1 para terminar na telemar
exten => _X.,1,Noop(${EXTEN})
exten => _X.,2,Dial(DAHDI/g1/${EXTEN})