We are replacing all our 2620 routers with 2821's. We (mistakenly?) assumed the 2620 serial interface modules (WIC-1DSU-T1) would work in the 2821's.
The modules do not show up in a "show version".
Do we have to replace all our WIC-1DSU-T1's with WIC-1DSU-T1-V2's? Or something else?