Is it possible to reduce the volume of dialtone in DISA?

I am connecting a Telular Fixed Cel station to my asterisk through a Wildcard TDM400P trunk. When I call through this device into asterisk, it picks up fine, and then goes ahead and takes me through the IVR and the DISA authentication…but after I succesfully authenticate, when asterisk provides Dial tone, asterisk is no longer able to detect the dtmf signals in order to complete my call. I called telular support and they told me its probably a a gain problem. Since the dial tone is really loud, and the call is coming through a cell which reduces its volume, the dial tone drowns out the dtmf and i am therefore not able to make calls.
any idea how I can reduce the volume of disa dial tone? or kill it all together? Maybe just leave silence after it says Thank You?

I have a similar problem.

Sometimes, asterisk detects some inputs, sometimes not, depending on the cellphone used.

Did you find a solution ?