[asterisk-users] zaptel digit problem

hi, all
I am using asterisk 1.2.12.1 and zaptel 1.2.7 and libpri 1.2.1 version.
I have created Ivrs(very big) .It works fine in sip phone , but when i call
through zaptel digit sens problem occured. Asterisk doesn't sens any digit
pressed.Our pstn is CORAL pbx.
any suggesion..
thnks,
Bhrugu Mehta(india, gujarat)