many ways 2 debug this… some loops r wrong (or too complx til bugs r fixd). ur code has no err chking so how can u find the problem???
examples:
add serial tap 2 chk io to sim900a (connect 2 pc via max232 or similr n thn use hyprterm)
or add i2c lcd display n add code to out all recd data to lcd
or add soft uart code in microc compiler n out all recd data to it
or use microc sw simulatr