I am able to connect my sim900 gsm module with hyper terminal but I am not able to connect it with 89s52. Please help me to connect it.
You say it "works" with Hyperterminal - so what have you done to determine what's different between that and your 89s52 setup? (you've already had a hint about observing the module's responses, and the speed at which you can send commands manually)
What have you learned from the large number of posts already on this forum on this very topic?
What have you learned from the vast number of posts all over the interweb on this very topic?