[c-nsp] config smart serial port

[s m]

hello guys,
i have a 2800 router with a wic/2t smart serial module on it. i want to
check these serial ports and learn how to config them. i googled so much
and understand that smart serial ports should be connected to a modem or
another smart serial port on another router (please let me know if i
misunderstand). i don't have any modem or another router.

is it possible to connect two ports of the same module together and config
these serial ports? (something like loop back) and if it's possible how i
can do it? (what commands are needed?). i just want to know how this serial
port works and should be configured.

thanks,
sam