Dtmf not Accepted in outbound calls

Hi all,

I’m using asterisk 1.6,Dahdi,libss7 and dialer card for ss7 e1 lines . When i tried dtmf is not accepted in outbound calls.

Please find the configuration file as below.

[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
callgroup=1
pickupgroup=1
immediate=no
signalling=ss7
ss7type = itu
ss7_called_nai= national
ss7_calling_nai= national
pointcode = xxxx
adjpointcode = yyyy
defaultdpc = yyyy
networkindicator=national

Please help me to solve this issue