Sim868 gps rxd, txd

Hello,
I have a question regarding SIM868 module’s pins. My SIM is on its own and I want to use GPS. Module has GPS_RX and GPS_TX pins. Are they nessesary for getting longitude and latitude from antenna or they are just for upgrading firmware of GPS?
I do not have them used in my circuitry.
I am passing informations from SIM868 to Atmega328 via UART1 on SIM and everything (Bluetooth, GSM) works but GPS does not. So I am wondering if those pins are needed.

Thank you for any help.

Vojta
( I am new here, be kind :slight_smile: )