U have to use COM4 in ur case.
I have just completed the article from
and it works fine 4 me.
Check u are opening the correct port at ur mobile application.
I was stucked when I tried to do it as
I was wrong
comm = (CommConnection) Connector.open("comm:com1");
works fine 4 me.
comm = (CommConnection) Connector.open("comm:USB2");
I am using Nokia N79. We both have mini usb cable. So U also have to use comm:USB2#
And sometime hyperterminal read the given output when the outputstream or the commconnection closed.
I faced this problem.