I know nothing about analog trunks as we don't have them here for years now.
And I know nothing of your national/international numbering plan.
Knowledge of both is needed to give you a solution, but I think this happens:
You have a shortcode 9N,N,dial,50:Main and a shortcode 9001N,001N,dial,50:Main force auth code ticked
Now if you dial 9 and just wait then when the system dial delay time has completed you are send to ARS and you'll get dial tone and can dial any number you like.
So you should avoid that.
A simple mind delivers great solutions