Ask your provider if "Clip no Screening" is enabled for your trunk.
Also ask them if you have to send pai or sendrpid only.
Otherwhise it wont work.
Some providers ask for a agreement that you are responsible if you show probided caller ids with your trunk and after that they enable this feature.
Thats how it works in europe/Austria by the most providers.
But the key feature is called "Clip no Screening"