Hello Mario,
First off, this is not possible with CCA, this can only be done though CLI.
1. Setup seperate PSTN Trunk Groups. A: 0/1/0, 0/1/1, 0/1/2 B: 0/2/0, 0/2/1, 0/2/2
2. Setup Dial-Peers for each Trunk Group.
3. Setup COR list to restrict which users can use either Trunk Group.
That is the simple explaination, the actual setup can get quite complicated and lengthy.
Thank you,
Darren