Sync port of 2501 will support E1/T1
Built in WAN port of 1601R will support 115 Kbps async and 2048 Kbps sync, will support T1/E1
2610 has one ethernet and 2 slots for WAN modules. Check the module installed :
The WIC-1T / WIC-2T is the WAN module that will support 115 Kbps async and 2048 Kbps sync
This will support E1/T1
The WIC 2 A/S is the sync/async module that will support 115 Kbps async and 128 Kbps sync
This will not support E1/T1
Regards...Ketan Chaudhari, CCSA, CCNP, MCSE