I just install two HWIC-4T1/E1 on Cisco Router 2921, but i don't see the interfaces in the show ip interface brief? Do i need to add some commands to enable the cards or the interfaces ? www.router-switch.com/hwic-4t1-e1-p-1132.html
these cards HWIC-4T1/E1 require IOS 15.0(1)M on Cisco Router 2921 according to: www.cisco.com/.../product_data_sheet0900aecd80710c77.html
Have you ckecked this ?