I have been fighting with this same scenario. I am using a PRI with DID trunk type. You won't be able to forward direct to a DSC like this. I had to setup a dummy acd to send the calls to which DCFW'd to a CDP DSC where the first digit is something different. That then is sent to the PRI with a DMI table changing the first digit back to what it is on the dummy ACD. That seems to work. If you can do QSIG, I would suggest it. If QSIG, you should be able to set the trunk type as TIE and won't have the problem. Or, try to setup NI-2 TIE with CBCR:NO. That is what the 3rd party docs are telling me to do, but I can't turn off the CBC package.
I am interested to know how this turns out for you so keep this post up to date with your results.
My current setup works, but is kluge.
Rob