Asterisk ss7 sangoma card caller id / billing with interconnect

We are interconnected with a ss7 E1 provider and can make live calls. We want the provider to see a caller id and the person receiving the call must see unknown or blocked etc but not the caller id we have so far tried issuing different ani,num etc. Seems like the provider is using the callerid(num) in their cdr. I am seeking someone who has further knowledge on how to hide the caller id from the person being called while sending it to the provider