Compatible Systems 1220I - Manual (Page 14)

8 Chapter 2 - Getting Started
RS-232 Interface
The MicroRouter 1220i includes one DB-25 to DB-25 RS-232
sync/async cable. This cable supports RS-232 asynchronous modems,
synchronous leased and switched 56K CSU/DSUs, and ISDN Terminal
Adapters. It can also be used to connect the router’s auxiliary interface
to a PC running terminal emulation software, or to a dumb terminal.
v Note: Please use only the supplied DB-25 cable when connecting
your line communication device to the MicroRouter 1220i’s RS-232
interface. The cables provided with other equipment may not have all
of the same internal connections.