How to wait for '>' in SIM900 message format
If you are interested in receiving certain character on UART irrespective of time, then check UART interrupt section. You can do like this,
-Enable UART reception interrupt.
- In while(1) -Infinite loop
-As soon as it receive data then check whether it is expected or not. (In your case it will be'>')
-And when you receive the expected data you can either disable interrupt, stop communication or go for other task.