@Ogu Reginald
I have only interfaced GSM and GPS with 5V PIC. The SIM900 pins are 2.8V TTL, I guess. I have used SIM900 which already have level converters for 5V and 3.3V TTL. If your GSM and GPS modules doesn't have 5V TTL interface pins then you have to use level converters for interfacing with 5V PIC. If you want to both send and receive SMS then cross connect GSM to PIC UART pins that is Rx of GSM to Tx of PIC and Tx of GSM to Rx of PIC.
@Vineeth
Do you need formatting of latitude and longitude values ?