When I connect gsm with lpc 2148 I am not receiving any response from gsm. Program is correct I have seen it's output on hyperterminal.what can be the problem please help me.
Not really made a convincing argument that the software or connectivity is correct. This is a topic area where vagueness and non-specific descriptions will get you nowhere.
TX on modem would likely want to go to TX on micro-controller. Check naming and connectivity expectations. Check baud rate, and voltage level expectations.
Does the modem have a part number? Does it have a manual? How have you connected it up? Does it power up? What does your software look like?
I have made cross connection that is tx of controller is connected to rx of gsm sim 900. Gsm modem is power up by 12 volt adapter and controller by 9v. I have check program in keil5 in debug mode everything work fine.
So which part of, "TX on modem would likely want to go to TX on micro-controller" did you not understand?
"Check naming and connectivity expectations. Check baud rate, and voltage level expectations"
Have you done that?
See: www.avrfreaks.net/.../2356086
Try monitoring the comms between your GSM and microcontroller:
www.avrfreaks.net/.../2306116
See also:
www.avrfreaks.net/.../2336161
Note that this has nothing to do with Keil!