The correct interface does depend on the way that the E1 is terminated, but it could need a serial interface, a WIC-1T or WIC-2T, if it is X.21 or V.35, with the appropriate cable, or it could need the VWIC-1MFT-E1 if it is just presented as a ‘raw’ E1 circuit, probably 120ohm balanced with an RJ48 (which is physically identical to an RJ45), or as G.703 coaxial (75 ohm), so you will also need a balun and probably a short run of coaxial cable.
Post a copy of the config (remove any passwords and IP addresses and replace with XXXX or xx.xx.xx.xx), and a copy of the ‘show hard’ and ‘show cont’ commands.
I suspect you do not have the interface you need in the router, but that extra information should help to determine if that is the case.
I disagree. I think the command needed is the “card type e1 <slot>” command. This will create the controller interface, and then after configuring the controller interface, you can create a serial interface.