Controller not able to collect response from GSM Modem

Hello all, I am trying to send Command from 89S52 Controller to SIM900 GSM Modem when i am sending command as "AT" in response my Receive buffer is able to receive all bytes and code is working...
Controller not able to collect response from GSM Modem

Hello all, I am trying to send Command from 89S52 Controller to SIM900 GSM Modem when i am sending command as "AT" in response my Receive buffer is able to receive all bytes and code is working...
89S52 not able to receive complete AT Response from SIM900 GSM MOdem

Hello I have connected SIM 900 (GSM Modem) with 89S52 Controller, via RS232 Communication. If I send AT from controller to Modem , it is replying with AT OK but my controller is just able to receive...
89S52 not able to receive complete AT Response from SIM900 GSM MOdem

Hello I have connected SIM 900 (GSM Modem) with 89S52 Controller, via RS232 Communication. If I send AT from controller to Modem , it is replying with AT OK but my controller is just able to receive...
Gsm modem interfacing with lpc2148

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.