Per call coming in would have to be from the other side. Per call exiting the SIP trunks, something like this should work:
voice grouped-trunk SIP-OUT-TG
description SIP trunks outbound
I went ahead and flagged the "Correct Answer" on this post to make it more visible and help other members of the community find solutions more easily. If you don't feel like the answer I marked was correct, feel free to come back to this post and unmark it. If you still need assistance, we would be more than happy to continue working with you on this - just let us know in a reply.