Sim800l with the mkr1000

I would like to use a Sim800l when there is no wifi connection.

My wiring looks like this:
VCC -> Battery (3.7 V)
GND -> GND
TX -> ~3(D7)
RX -> ~4(D8)

The thing is with the mkr we cant use SoftwareSerial.h so iam kinda stuck. I tried this with sercom5 but i totally dont understand this.
Basically i just want to send AT Commands and get a response or at least get the status from the Sim800l

Can anyone help me with this?