By default Cisco routers doesn't have serial ports. Therefore we need to add a serial port to router.
- first, open CISCO packet tracer software (if you are not currently working with one)
- then, drag and drop any type of router from the bottom of the interface in to the middle of the working area ( i have used 1841 router here.
- Click the Router--> select Physical tab-->select WIC-IT -->switch off the Router-->add the Serial port to the router (drag and drop the serial port that is displayed in the right bottom corner to the space given) -->switch on the Router