I found a work-around for this - DNIS substitution 1NXXNXXXXXX ---> 11NXXNXXXXXX
I actually found, likely the true correct answer.
Adtran ships the box with ISDN Number Templates applied. You can access the page from the webui Voice->ISDN Num Templates In there it states:
ISDN Number Templates look similar to standard dial plan templates but are used exclusively by ISDN-based trunks to recognize dialed numbers as a particular type of call. Additionally, if a prefix is specified, then the number template matches against that prefix as well but strips those digits before sending the number.
There is a default template in there for National calling with a Prefix of 1 and then NXX-NXX-XXXX. According to this Num Template rule the 1 is stripped from the message sent out the PRI when you have a dnis of 1-NXX-NXX-XXXX
Then best thing is to delete this rule from the webui or from the CLI with the following command:
no isdn-number-template 6 prefix 1 national NXX-NXX-XXXX