First be sure that an emulator is running.
Then open up the console with Start >> Run (or press Windows + ‘r’) and type in ‘cmd‘.
This will bring you to something like:

Like shown above, type in ‘telnet‘ and press enter. The result will look like:

Here type in ‘o localhost 5554‘ as shown here:

This will establish a connection to the emulator.
You can see the port number to be entered in the title bar of the emulator window.
If this succeeds, it will open the Android Console:

Here you can use all kinds of commands.
To simulate a call, type ‘gsm call 066712345‘:

The result is an incoming call at the emulator:

To cancel the call, type ‘gsm cancel 066712345‘.
See http://developer.android.com/guide/developing/tools/emulator.html#telephony for more information about gsm operations.
Use ‘exit‘ to exit the Android Console and ‘quit‘ to quit telnet.
Hope that helps!
thnks for giving such a good descripion.
tks! great!