Arduino DUE + GSM

In my project I need to send SMS on specific events (i.e. reading temperature sensor values over a treshold).

For what above I bought and Arduino Due and a GSM board (SIM800L)

I'm now wondering if I can directly connect the TX and RX pin of the GSM board (that is powered with +5V) to one of the RX/TX pin of the Arduino Due board. Is the TX/RX level of the GSM board compatible with the Arduino Due?

Do I have to put a bi-directional level shifter (3.3 V to 5 V) between the RX/TX pins of the Arduino and the pins of the GSM board?

I don't want to burn the Arduino Due :o

Any help is welcome!